Guide: Battle Strategy

Please Note This is a guide written by Asjo for the .EN forums. It is long, but well worth the read. It assumes that you have knowledge of how the Battle System works.

In Grepolis, no player can accomplish much on his own. You can never conquer all you enemies alone, even if you are only held back by lack of available city slots. And as long as the enemy is strong enough, you will never be able to defend yourself alone. Once you have a group of players who know this, and are willing to act as one, you can start playing as an alliance. This is where warfare becomes interesting ... and a little more complicated. This guide will explain how you handle large-scale wars and conquests with several people involved as well as walk you through the kinds and finer details of attacking or defending.

Please bear in mind that this guide will have some elements that are only relevant for conquest worlds. Any specific times mentions are based on worlds with unit speed 2.

Positioning

When you defend, you have the advantage of being able to stack your units and gain advantage in numbers. If 2000 slingers attack a defense with 500 swordsmen and 500 archers, the defense will not be particularly effective. However, if the defenders had ten times those numbers (that is, 5000 swordsmen and 5000 archers), they would be 45% more efficient. Now, if you consider that defenders already have city walls and towers which, when fully built, will give defenders 151,9% defensive bonus over the attacks, this means that you don't want to fight more defensive troops than you have to.
The reason that the positioning of cities is so important when you fight other alliances is that you don't want to give them the chance stack defense in their cities. Because of this, you will always want to have a city within one island of your target that you can lauch from. Since colony ships are slower, your clearing waves and support should be able to reach the target city in time, even if other cities are further away. When two alliances go to war, they will almost always end up with one or two big fronts against each other, with no or little mixing of cities on each side of these fronts. If you have cities in the midst of enemy cities, they will likely have many more cities that will be able to reach those cities than you will have cities that can send support in time. Thus, cities in in the middle of your enemy area will often be quickly captured or will take a lot of effort to support or sustain.
Normally, what you should do in is not just to get all alliance cities within a limited area, but also to get them on the same islands. If you are able to cluster up your cities and cover a smaller area with more alliance cities, you can cooperate more effectively. The distance of one island might not mean much, but if you don't cluster up cities, you alliance might be streched over twice the space, likely meaning that if you are attacked at one end, you will not be able to defend with over half of your cities, because they are too far away. An added benefit of having several cities on the same island is how quickly these can reach each other, should one of them be attack. If a city is under siege, other cities on the same island will be able to ignore the ships defending it and siomy try to kill the ground troops and breaking the siege in this way. It goes without saying, of course, that no player should have more than one city on the same island (as only one city per player can use farming villages), so if this ever happens, the city should be handed over to an alliance-mate.
Generally, you will want your offensive cities to be near the front, and the defensive cities slightly behind them. If any defensive cities are very far away from the front, you can send their troops in advance to those of your cities that are most likely to be attacked. Against a really strong and active alliance, it can be very hard to take a city if your colony ship takes over three hours to get there. What you can do is that you get some cities on the same island as the enemy alliance. You can colonize it if you have to, and wait a few weeks for it to build up. Then you can launch from this city. Attacks and support will likely take longer than the colony ship, so these should be sent in advance. Using this methods, you can gain ground on your enemies even when it seems impossible, since you will be able to start a siege in something between 1 and 1,5 hours, and you only need enough biremes to be able to hold the siege.
To get a proper overview of positioning, Grepolis Maps is incredibly useful. It can quickly show you where all the different alliances have their cities located:

Conquest

More often than not, many elements will have to be involved in a successful conquest. You need planning and coordination and you need to be prepared any tricks the defender will come up with. If you are very new to attacking and want a bit of basic information, you will want to read my raiding guide.

Planning

Whenever you go for a city of an enemy alliance, it's highly recommended that you plan in advance. Very few alliances have so active and plentiful members that you can just post the arrival of your colony ship and expect a lot of clearing waves and support to arrive in time. The advantage of attacking without planning in advance would be that it doesn't leave room for any spies within your alliance to pass information onto your enemies.
In order to be able to properly plan and coordinate, it's important that the alliance agrees on certain time settings and that all members use these settings. Once this is done, you should be able to set a certain time and see whether everyone can join in. Setting a time allows everyone to build up for the attack and have full favor for the gods and full population for their attacking cities. You also need to be sure that you have the necessary amount of troops, so that you don't only have a lot of normal attacks with offensive units and light ship escorts, but also have some light ships nukes (attack consisting of big amounts of light ships - typically around 260 when fully built) to go first and break the biremes that will likely be awaiting you once you reach the target city. Likewise, you not only need to be able to start a siege in the city, but be able to have enough ground troops and biremes to defend it once the other alliance tries to break it.
Spying in advance of an attack can be a bit tricky. It can be an advantage to know what's in the city before you attack it, but normally it's not really necessary for large-scale attacks. There are only a few reasons you would want to know what's in a city. It would be useful if you doubt you have enough offensive units to break the initial defenses and would rather target an enemy city with offensive units. Also, if you launch attacks to clear the city at the same time as you send the colony ship (to kill the units early and avoid them being there to snipe the colony ship later), knowing what's in defense helps you determine how much you need to send ahead. What you should try to do is to gather as much info about enemy cities as possible. Once you have seen what cities typically send for attacks, support or light ship nukes, you can have a good idea or what kind of defense they might be able to muster. If you spy, I siggest that you do it some time before do the conquest so as to not give your intentions away if the target city has a lot of silver in the cave (which it likely will). If a city is spied a few times, some people might take precautionary action, but if nothing happens, they will likely let things go back to normal. A ground attack from the same island can also be an alternative to spying and reveal if a large amount of biremes/transports are holding in the city before you commit to an attack.
One thing you might consider in the planning is that the player who has the siege will get more battle points. The distribution of battle points is decided by the amount of population each player has in the city that is attacked, but the person who owns or occupies a city will always get at least 30% of the battle points of any battle. So, if you have some players with fairly few culture points and others with many, it might be a good idea to let those with les culture points do the siege. After all, you need less culture points to get more cities at the low culture levels, while once you get up to higher levels, each culture level will take several hundred culture points. So, the battle points gained from defending a conquest might help one player get enough culture points for six new cities will only help another player gain enough culture points for one city. In morale worlds, you can heavily abuse the morale-system by letting low-point players capture the enemy cities; this is not something I can advise you to do, of course.

Coordination

Being able to make well-coordinated attacks is the alfa omega of conquest. Basically, what you want to coordinate is the following:

• Light ship nukes: Light ship nukes should preferably hit first, clearing the city of biremes. If biremes aren't cleared by the time clearing waves arrive, many transports will likely be killed, meaning that many of your offensive land units will die without ever participating in the fights. That said, some light ship nukes should arrive among the clearing waves as you have no idea of what support is arriving at the city when (sometimes bireme support will be timed specifically to snipe your colony ship, whereas, in other cases, all support will just be send in advance). Keep in mind that even if you decide to send your clearing waves as breakthrough-attacks (which is generally not recommend), many transport ships will still die, and you can never conquer a city unless you clear it completely of both ground groops and navy (with the exception being fire ships, which do not fight against the colony ship).
• Clearing waves: These will basically be offensive land nukes (a city only building offensive land troops). As you would with any attack, you should include a light ship escort (usually 40-50 light ships). These attacks will have to hit between the light ship nukes and the colony ship. You will want them to land as close as possible to the arrival of the colony ship so the colony ship will not fall victim to a defensive snipe (see further down) or support from another city sent to intercept it.
• Support: You need your support to arrive as soon as possible after the colony ship arrives, to protect from any incoming attacks sent to clear the conquest and to avoid an offensive snipe (see further down).

To coordinate, you will at least need to know whose units are the furthest out. Normally, it would be preferable that no attacks that participate are slower than the colony ship, but sometimes that cannot be avoided if you lack the necessary firepower close by. If the slowest attack is not the colony ship, the arrival time of the slowest attack should be given to the player launching the colony ship so that it can be timed to arrive after that attack (if you send several attacks before the colony ship, you need to know which of those arrives last). Once the colony ship is launched (time to arrive behind attacks sent before if necessary), its arrival time will be shared so that people can time their attacks and support more specifically. You can see the specific arrival time of an attack by click on its icon in the troop movement overview:

Something that is extremely important to keep in mind when timing attacks is the anti-timer that has been implemented in Grepolis. It keeps you from being able to precisely time your attacks, adding an element of luck. Every attack you send will suffer a random offset at its departure that can be anything from 0-30 seconds +/-, with the maximum offset varying between worlds. It is crucial that you know what the maximum offset is in the world that you play in. I have done a test in Phi by sending out attacks several hundred times and recalling them. By noting down the difference between projected arrival time and actual arrival time, I have been able to surmise that the maximum offset for Phi is +/- 12 seconds. That means that if I send an attack, it could arrive up to 12 seconds earlier or 12 seconds later. In the above example, the attack is launched in Phi. The colony ship arrives at 7:26:39, so that means that All clearing waves should be sent to arrive at 7:26:26. That means that the latest they could arrive is one second before the colony ship (+12 second offset), while the earliest they would arrive is 25 seconds before (-12 second offset). If you have a lot of offensive troops and know you likely won't need them all, you can try to get the timing closer to the colony ship and simply recalling your attack if it doesn't get the right timing (to avoid it accidentally arriving after the colony ship and attacking your own siege). The same goes for support. In the above example, all support should be sent to arrive at 7:26:52, meaning that none of it has a chance of arriving before your colony ship does. This tool, although it's made for another game, can be useful if you want to calculate when you should be ready to send your attack to have it arrive at a specific time.
If you are quick, one way to get a good timing is to send several times, recalling when you don't get the right timing. So, you might send your first attack 4-5 seconds before the time you want to hit, hoping for a delay. If you don't get it, you recall right away, send again. If the timing still isn't good, you recall once more and resend. Of course, the greater you antitiming offset it, the earlier you can make your first attack, so in worlds where the offset is very big (30 seconds, for instant), you can make more attempts at getting a good timing. If you are attacking with fast transporters and use a single normal transporter for timing, you can try this two times; once with the timing of the normal transporter, once without the normal transporters, with the timing of the fast transporters. Another trick is to send any units that you don't want to send out of your city in advance so that they are stationed in another city. That way you can make use of the 'Select all units' button to select all units easily when you re-send.

Execution

There are some important ground rules for attacks:

• You should always cast as spell on your conquest attack to protect it from spells from the defender. Your colony ship will likely be killed if a Sea Storm is cast on your attack since it takes up a significant part of the population in your attack, therefore being more likely to be hit.
• An attack can be recalled within the first ten minutes, so if the defender casts a spell on your attack right away, just recall it. Never recall it if all your alliance-mates have already launched their attacks, though - then you have to go through with it to avoid them being caught in an unfortunate situation. Note that you won't get notified if the defender casts the spell Desire on your attack, but you will be able to see if it has been casted by checking the attack.
• Once your colony ship arrives, always make sure to recall the offensive units that arrive with it (select 'return several units' in agora of the attacking city). You do not want these to defend, so you are better off just recalling them before any attacks arrive to try to break the siege (mind you, you are required to leave one units and one light ship with the siege):

• Mind the "insufficient units" bug. If you have units building in a city where you launch an attack, you might get an error saying "Not enough units in this city". This happens when you keep your attack-window open and a new unit is built in the meantime. So, don't keep your attack-window open for a long time if a unit is about to pop out (you can check unit progress in barrack and harbor).
• You should always try to attack at times where your opponent might be sleeping or away at work/education, since these will be the best windows to strike. Always keep in mind to take note of the online times of your opponents. If you need more information, send random attacks to find out when your opponent is online and to keep him or her guessing.
• If you care to make the effort, it is useful to time decoy clearing attack for your colony ship. It have the potential to make the defender waste his spells them and can also confuse the defender about the intention of your attack. At the same time, it can also give a false impression of overwhelming attack power and affect the defender's decision to send support and how to time it. If you have three attacks arriving shortly before the colony ship, a defender who is short on units might recall his support if he is not able to time his support to arrive after those attack, since he does not want to lose small remaining defensive force and assuming that you are sending full attack forces, not decoys.
• Allowing some of your attacks to arrive at the target after your conquest attack arrives can we very useful. Just like when you attack your own cities, the only thing that will happen when you attack your own siege is that you get a message saying that your troops visited during peacetime. However, many defender might assume that the last attack is the conquest attack or think that since more attacks arrive after your conquest attack, it is simply a decoy for one that will be sent later. Additionally, if you have a lot more units in the area than the defender, you will have the chance to kill his support so that he has nothing to defend if you launch another conquest attack. If your conquest attack is killed, your attacks that arrive after the conquest attack will be able to kill the units in the city, which it is unlikely that the defender will be able to remove in time.
• Never include mythical units in the support you send for a siege as it is likely your support will never arrive at the city, since you can only support cities that have the same god as the mythical units.

Attack composition

If you follow the multi-city guide and specialize your cities, you should be set for a good attack combination, not matter what combination of offensive units you choose. You simply need your attacks to be as big as possible to make sure that the advantage in numbers never falls too far into the defender's advantage. If you spot that the defender has a weakness, for instanace building too many swordsmen, you can adjust your composition to be more effective (for instance, including more sharp attackers, which kill swordsmen more easily). If you have pure nukes, meaning attacking cities that only produce one specific attack type, without mixing the different attacking units, this adjustment becomes easier.
Mythical units can be excellent to include in your attacks, if you can build up a significant amount. Normally, people will have defenses that are a little weaker against sharp attackers, since chariots and hoplites aren't as effective attacks are slingers and horsemen, with only 14 and 16 attack points per population respectively. However, medusas are sharp attackers and have 24 attack points per population, so they can do quite well against most defenses. Manticores and harpies, both effective attackers, are flying units and do not take up the capacity of your transport ship, so if you build these they will allow you to build up a bigger offensive nuke, with more offensive units and less transport ships. Only build the mythical units if you know that it's unlikely you will need the favor for other things, though.
Using normal transport ships will allow you to include more offensive units in your attack. Therefore, using normal transport ships in your offensive cities is preferable. Normal transports are slower than fast transport ships, but if you only keep offensive units at the front towards your enemies and convert the ones further away to defensive cities, this will never be a problem. However, if you find that there are several action zones and you have too many offensive cities unable to participate due to not being able to get there in time, you should switch your cities from normal transports to fast transport ships.
For bigger attacks, I greatly recommend that you send some attacks that arrive at the city early, before any additional support will reach the city. These attacks should be launched at the same time as the colony ship so as to not give the defender any advance notice of the incoming conquest attack. The purpose of these attacks are two-fold: 1) to kill the defending troops so that the defender cannot make a defensive snipe 2) knock down the city walls. If the city wall is fully built, you will typically lose 2-3 times more units than the defenders do when you try to take a city. However, if you send two attacks consisting of, for instance, 1200 slingers and 50 catapults, you can manage to knock down the city walls before your attacks arrive. If you send catapults in clearing waves to arrive just before the colony ship, chances are that too many defensive units have arrived and your catapults will not do much damage to the walls. But even against a maxed out defense in a city, a catapult/sliger nuke can do considerable damage to the city walls. However, once several thousand defensive units have arrived, such an attack would do almost no damange to the city walls. The points is to knock down the wall so that by the time your clearing waves arrive, they can fight without a high level city wall present, yielding much better results.
You should expect your enemies to be able to get a lot of biremes to defend their cities. It would likely not be too far off to expect every fifth city of theirs to be a bireme city (a city that has 300-350 biremes). At any point in time, it is likely that it will, on average, be at half strengh (say, 150 biremes). Whenever you attack the alliance, it is likely that they will get at third of their biremes to defend the target city. Similar numbers go for the light ships that they will send to break your siege. So, this should give you an idea of what numbers to expect, but an even better measure is your past experience and concrete intel you have on the alliance.

Fake attacks

At some point alliances and players get so big that their defenses can seem unbreakable. Therefore, decoy attacks become a natural part of any conquest attempt. The idea is that you launch one or several conquest-attack somewhere else to distract from your real attack and draw support there. An alternative version is that you launch conquest-attacks at different times towards the same city, making it impossible for the defender to know which attack to time a defensive snipe against. The defender might try to snipe one of the fake attacks, only to find that it's fake and have his defensive units wiped out by the followign clearing waves. He might also dodge the initial attack, assuming that it's a fake, only to find out that it was the real attack and the following attacks are simply 3-4 light ships.
The timing of a decoy attack should be such that the defenders will not be able to recall their support and send it to the real attack. It is also crucial that the decoy attack looks exactly like a real one with both clearing waves and support. When you attack, your attack always has to consist of 3% of the total amount of population in units that belongs to that city. So, if the city has a total of 2000 population worth of units, any attack would have to contain at least 60 population worth of units. So, if you send light ships for your fake attacks, which would be a natural choice, you would need to include six in each fake clearing wave, whereas if you have cities with low population, you migth get away with sending just 1-2 light ships. If you usually attack with normal transport ships, you should build a normal transport ship in all the cities that send fake attacks and include them in the attacks so that the attack times will match those your enemy expects (might also make it easier for you to hit the right timing on your attacks, at least giving you two chances to do some; the slower time with transport ships and the faster without). There is no limit to the amount of units you are request to send to launch a support-mission, so I recommend that all fake support waves simply consist of a single normal transport ship.
You should consider the following rules for decoy attacks:

1. All fake attacks should be hidden through the use of spells that you cast on them. If you have cast a spell on your attack, no other spells can be cast on it, and therefore it cannot be revealed by Athena's Wisdom spell.
2. You should never send more than one fake attack from one city
3. You should never send a fake attack from a city where you are sending a real attack from
4. Any city from which you send a fake attack must have at least 4000 points (to make it believable as an attacking city)
5. Never send fake attacks from a city that has recently been revealed to your enemies as being a defensive city or one without many troops in it

Holding the siege

To hold your siege, you will need both biremes and defensive support troops to arrive after your colony ship. You need both, since, if either you naval units or ground units die, the colony ship with be destroyed as well and the siege will be broken.
Once you land your conquest attack and start your siege, you can keep track of incoming attacks and support by clicking the icon of the siege and selecting the 'Troops' tab:

You will not be notified of attacks, so if you are doing several conquests at the same time and don't know where to send your support, you should keep checking this tab regularly. Notice that you cannot cast spells on the attacks that are coming towards the city where you have your siege.
Should your siege get broken, it is important that you withdraw any remaining troops. Otherwise your enemies could attack them and gain both the offensive and defensive battle points for killing them.

Gathering intelligence

When you make attacks against an enemy, it is always a good idea to take a screenshot of your city wall, where you can see how many troops you have killed (when checking the killed units, you can also check whether your opponent was online and enlisted militia). If you lose the battle and you are not able to see how many troops you killed, you can often figure out the magnitude of the defense using the simulator. If I attack a city with 100 light ships that all die, I will not receive any information about how many ships I killed. So, I will check my city wall and compare it to the screenshot to see how many ships were killed. If I killed 73 biremes, I can run the result through the simulator (remember to input morale, luck and other bonuses) to figure out how many ships had to be in the city in order for the defender to suffer this exact loss. If you have been attacked from that city before, it will be easy for you to check in the simulator whether that player has the Captain premium bonus or has researched Battering Ram.
Any time that another alliance tries to take your city, make sure to note down which support is sent from which cities. If you attack them later, you will have a very good idea of which initial defenses to expect.
If you attack a city with ground troops from another city on the same island, you will be able to see all the ships in the city, even if you lose all yo. This is not only useful to see the amount of biremes and transports that your enemy will stack in a city if you attack it, giving you an indication about the amount of defense that player can send in support.

Defending Against Conquest Attacks

In conquest-worlds, there are a lot of possibilities for defenders to kill off attacks on their cities. If you only have one city, no friends, and you're put under siege, this system is very merciless. In fact, you can never really rest assured. However, should you be online, there are various things you can do, and I will try to describe how defense works below. If you have very little experience how defense works, you can read more about that in my defense guide.

General pointers

• If you have an incoming conquest attack, don't cast any spells on it right away, unless you hope to kill the colony ship with a Sea Storm before the attacker puts a spell on it. The attacker can recall within the first ten minutes of an attack, so unless you want to cast a Sea Storm or Zeus' Rage on the attack and hope to discourage it, you should wait out the ten minutes.
• If you see an incoming conquest attack and know that you can send a lot of support in time for its arrival; play dead. Don't give any signs of life by casting spells. If you are dodging attacks from the attacker or people associated with the attacker elsewhere, do not summon militia and be careful not to show that you have dodged by leaving one of two units that came through the production queue in the time between your dodge and the arrival of the attack. You can also apply this mentality to normal attacks. Any incoming attack might be a conquest attempt in the making. Never show that you are online too soon.
• Use fast transport ships for all your defensive cities, unless you keep their troops permantly stationed somewhere else. It is essential for being able to get to the the city being attacked quickly, especially if your alliance is spread over a big area
• Your enemies will sometimes to send messages to your to figure out your online times or simply to check if you're online at the moment or can be attacked. When you send a message to someone, you can see whether they have read it, even if they don't respond. So, if you suspect this is the case, I advise you to not read/respond to messages from enemies at times where you would give away your online times (for instance, right when you wake up or get home from work), but rather do so at odd times or at times where you would not normally be online. Even if your enemies don't want to use it against you, they will subconsciously add knowledge about your online times judging from which times you usually respond to their messages.
• Whenever a city is attacked, all the supporting troops only gain the bonuses that the owner of the city has (including premium bonuses), while none of their own bonuses matter. So, even if you make a naval city where you have no intention of building ground troops, you should still research Phalanx, and likewise you should also research Battering Ram in cities when you only build ground troops. If you are online very often, you will also be likely to benefit from building Tower in your cities, whereas if you are no online very often, it is like that your enemies will benefit from you building Tower, since they will get the 10% defensive bonus once they start a siege in your city.

The role of naval units

In revolt-based worlds, you can more easily rely on using only biremes to defend yourself. You always have more than 12 hours to react to an incoming conquest-attempt, which gives you plenty of time to stack all your biremes in the targeted city and fight with a big advantage in numbers against the light ships while annihilating any land troop attacks by killing the transports. However, in conquest worlds the role of biremes is not so clear cut.
A big amount of biremes can do wonders if the attackers do not send enough light ships to screen for their attacks or do not send suffient light ship escorts with their ground armies. You can get a lot of cheap battle points this way. Having biremes always provides you a great tool to snipe an incoming conquest attempt, timing your support to arrive after most light ships have already attacked and easily withstanding the limited amount of light ships that are sent with the clearing waves and colony ship. However, biremes aren't fantastic defenders on their own. Whenever biremes are not stacked in their thousands, light ship nukes can do quite well against them. Against people who don't specialise their cities and maybe won't attack with more than 50 light ships at a time, a few hundred biremes can do quite well, but don't normally kill more than 150% of their worth. While the losses in the faceoff of light ships and biremes will be fairly even, the attacker will suffer much greater losses when facing a big defensive ground army in a city with high city walls. Therefore, you cannot really depend on either. You always need biremes to defend your own siege when you take cities and it's always worthwile to try to use biremes to snipe colony ships or kill off lightly-guarded transport ships, but you will always need the defensive groud troops to be able to take the damage when you face overwhelming odds.

Recognizing a conquest attack

When you are under attack, it is crucial to know if the attack is a conquest attack or just a normal attack. If it's a normal attack, you might simply dodge or send a few troops to incept, but normally a conquest attack requires you to enact more defensive measures. You can always recognize an attack with a colony ship by its speed. If you check the Grepolis Units Portal, you can see the speed of all units. Here, you can see that the colony ship is the slowest naval unit, and since fire ships cannot attack, no other naval unit is less than twice as quick. When you are attacked, there are three speeds that you normally need to consider:

• Attack with colony ship: The slowest of all attacks
• Attack containing normal transport ships: 2,6 times as fast as an attack with colony ship
• Attack containing light ship (and no normal transports): 4,3 as fast as attack with colony ship

To get the time it would take for a colony ship to attack a specific city, you simply select attack on the city that is attacking you and put '1' in for colony ship, and the time will show:

So, if an attack were to come from the city in the above example, I would have a better chance of knowing whether it was a colony ship. If I had been offline for five hours and logged in, I know that the attack would still have at least 2:54 hrs remaining (possibly less, if the attacking city has Cartopgraphy researched and yours does not), even if it was launched right after I logged off. There is no way for you to know exactly when an attack was launched at you. However, whenever an attack in launched at you, a notification of the attack will pop up on the right side of your screen. If you had reports or trades coming through while you were offline, those would also be listed on the right side. All these notification are listed chronologically, with the latest being on top. So, if the attack notification shows between the notifications for a trade going through and a battle report, you will know that the attack happened within that time frame.

Defensive snipe

When you are attacked, you most often have two choices:

1. Send massive support and defend against most/all attacks
2. Try to snipe the colony ship

You can snipe by sending units to support from other cities, but it can be hard to get the right timing because of the anti-timer. Sniping is done most effectively if you have units in the city that is being attacked. You need enough units to be able to defend against the one attack with the colony ship. If your city that is under attack has a lot of defensive troops, these might be sufficient to kill off the attack with the colony ship, at least if the prior attacks do not have catapults to take down your city walls. So, you can perform a defensive snipe by dodging all the clearing waves, only defending against the conquest attack.
The optimal timing for your support would be to arrive one second before the colony ship, but worse timing than that can often be sufficient. If you arrive on the same second as the attack does, the attack will always arrive first. As with timing attacks, you can recall and resend your support from other cities sevaral times to get a good timing, especially if the offset of the anti-timer is big, allowing you to send support that would arrive after the colony ship does, but instead arrives before the colony ship due to the anti-timer offset. If you are not quick enough with the mouse or don't have fast internet or computer, you might not be able to do the recall/resend in attempt to get a perfect timing. If a few clearing attacks arrive just a few seconds before the conquest attack and you don't have units in the city to snipe with, you might want to be risky and launch your support with an arrival that is closer to the arrival time of the conquest attacks, giving you a slightly higher chance of hitting the right timing but also risking that your support arrives after the conquest attack and is not able to participate. Another risk you might want to take is one that prevents you from getting too much support killed off. If you are up against a big alliance and know they have many more light ships than you have biremes, you might want to avoid fighting them unless you have to. If you have several bireme and light ship cities that can reach the attacked city in time, you might want to recall any support or attacks that get a bad timing. You likely need just one perfectly timed support or offensive snipe to kill off the colony ship, so you can make several attempts at getting that timing and save your city without many losses.
If a lot of clearing waves have been sent, it is likely that the attackers will have gotten a good timing with a few of these despite the anti-timer, and you might only have a few seconds between the last clearing wave and the conquest attack. If you have a good internet connection, you might find it easier to just dodge the last clearing wave right before it attacks (by sending your army towards a city on attack or support mission) and recall after a few seconds. If you want to dodge several minutes in advance and then recall, this tool might make it easier for you to make calculations (get the specific arrival time of the conquest attack by clicking its icon and insert this time as 'time of return'). Just remember, you cannot recall 10 minutes after your army has been sent somewhere, so make sure to do it before that. And if you send your troops to a nearby city and let them stay in support there, recalling them will count as a new support mission, so you will suffer the effects of the anti-timer. See an extensive example of a defensive snipe from the same city here). I recommend you test how the recall works on your setup before you use it for a snipe.
Here is an example of how a bunch of incoming attacks might look like, where the colony ship arrives seven seconds after the last clearing wave:

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Here is another attack, where the timing is much tighter:

In this situation, I still managed to snipe, but forgot to make a last-second enlistment of militia. You will want to prepare exactly what you want to do and keep windows such as farm for militia open (though minimized) if you think they will be necessary for you to make it.
In the following you can see an example of me sending my defensive troops away and then recalling to snipe:

As you can see, the timing of the snipe was unecessarily tight, since the colony ship arrived 31 seconds after the last clearing wave, leaving a lot of time to snipe. Sniping can be risky business, since you can end up getting your troops back too late, in which case they will attack the city and the occupying troops. This part naturally leads us to the offensive snipe.
One thing to keep in mind is that if you have lots of attacks incoming at the time where you need to recall, you might need to open the attack window to cancel your attack/support mission from there, since the troop movement window will be jumping up and down, making it very hard to cancel from there.

Offensive snipe

An offensive snipe works much like a defensive snipe. You send your units away and then recall them to arrive at a specific time. An offensive snipe works best when you have offensive ground troops and a low city wall or light ships in the city. Your aim will be for your offensive units to arrive back in your city just after the colony ship and before the first support wave arrives. If your units get back too late, too much support might have arrived, and you will not be able to kill off the colony ship. But if you have 100 light ships in the city, those will normally easily be able to defeat whatever ships are sent with the colony ship. Some players include triremes or biremes in the attack with the colony ship, which means that they will have some to defend right away, but it will normally not be enough to defeat as many as 100 light ships. Most players will only include light ships in their conquest attack, and these will very easily be killed off by just a few light ships, allowing you to kill the colony ship. If you have some offensive ground troops, these might also be able to defeat the offensive units sent with the colony ship and this break the siege (colony ship will also be destroyed if all supporting land troops die). This can also be done by sending attacks towards your own city from your other cities - just mind the anti-timer. There is no risk in attacking your own cities, since it's only possible for the attack to actually happen if you city is under siege. So, if you attack your own city but the conquest attack hasn't broken through, your troops will simply have a cup of tea and head back home.

Dealing with inactives

In any war, members going inactive will likely be a deciding element. If you have a tight knit alliance, everyone who wishes to leave the game will inform their alliance-mates in advance and make sure they can take all their cities at the same time, not leaving time for any enemies to take them once they discover the player is quitting. However, you might find yourselves in a situation where someone goes inactive and you don't know whether they are coming back or cannot take their cities right away. In this case, it is highly recommend that you send a tripwire to the city. A tripwire typically consists of a single transport ship and single unit. Sending these in support to a city means that you get a report notifying you of your support being attacked if someone sends an attack against the city. If your land unit dies but you ship survives, it cannot be a conquest attack since it would require both land and naval units. If the transport ship also dies, it means that all units in the city were gone or killed, and there's a good chance that someone has started a siege in the city, and you should send your light ships to attack the city. Often, people will not expect that they have to defend against a lot of light ships when they conquer the city of an inactive, so there is a good chance that you can break the siege with a single light ship nuke and keep them off the city. You would have to move quickly to take the city after that, though, as they will not make the mistake of sending limited support the next time. It is important to take the cities of your own inactive since you will otherwise leave holes within your own lines. If enemies get a city in the middle of all your cities, this can act as a launching platform for conquest attacks or as a place from which they can send quick attacks to kill off your offensive armies or light ship nukes.

It can also be a good idea to tripwire various inactive players and ghost town in your area if no one from your alliance is taking them just yet. If you decide to tripwire active players from your own alliance, you should send a bireme or unescorted transport ship (anything that won't accidentally kill off the light ships of your alliance-mate) to the city if the tripwire goes off. Once you get the battle report, you can see whether the city is currently occupied. Might be a good idea to send them a message if you're attacking them as well.