Fortresses, simply put, are a gateway to Capitals. Every city has four fortresses, and each fortress can only be owned by one alliance at a time. An alliance can have only one fortress in each city, but can have a fortress in every city if they can do so.
Taking a fortress is just like a Zero Hour battle. Any member of the alliance may start a battle in a fortress in the same city they live in. Whether the fortress is already owned by a different alliance or not is irrelevant. Any member living in that city who is online can join the battle. In each fortress in each city the minimum number of attackers is 8, and the maximum is 20. Once the battle starts, the rest is the same as any other Zero Hour battle, three sides must be won to win the battle, and if so, the alliance is then in control of that fortress.
The players who participate in taking the fortress will become the defenders, and the leader of the battle (Not necissarily the leader of the alliance) will become the Commander of the fortress. If a player is removed from the alliance, loses their account, or moves out of that city, they will lose their spot as a defender. If the Commander leaves his position as a defender, the highest levelled player (Town Hall level) will take his place as commander of the fortress. The fortress must have at least 8 defenders at all times. If too many defenders lose their position as a defender, the alliance will forfeit the fortress and it will become vacant again. The alliance may then try again with a new set of defenders. However, they may not add more defenders to a fortress they already own.
During the battle, if the fortress is currently not controlled by any alliance, 20 NPC legions will face the attackers, five on each side. If the fortress is owned by an alliance already, the attackers will face off against the defenders of the alliance, who will appear in the same positions they were in when they took the fortress. The defending legions will appear as they currently are, even if they have insufficient troops or no equips. The NPC legions average around level 20-25 in the 10-30 regions, level 40-45 in the 30-60 regions, and level 70-75 in the 60-80 regions.
Note: Fortresses can be attacked at any time of day, with the exception of between 10 and 11AM Server Time, due to this being the time when City Capitals can be attacked.
Capitals are what alliances should ultimately aim to own. Every city has a Capital directly in its center. The capital is surrounded by the four fortresses, the Capital Mine, and the Capital Farm. The Capital battle takes place between 10AM and 11AM Server Time every day, and any alliance in control of a fortress in that city may participate.
The Capital battles are the most unique battles in the game. When the battle begins you will be taken inside the Capital where you will see lots of different objects scattered across the screen. There will be mines, farms and houses. Just like a sanctuary quest; you will be able to click to one of those places if it is adjacent to your current position and travel there. If it is a mine, you will be rewarded with gold, if it is a farm, you will get food, if it is a house you will get troops. (Mines and farms also give troops, but not as much as a house.) Every click has a cooldown of 10 seconds, meaning you may visit up to 6 places every minute, you can spend the entire hour farming and mining to your heart's content.
Things get tricky is when more than one alliance is in the capital at the same time. Only one alliance may take control of the Capital so the alliances in the capital must fight until the hour is up for command of the Capital. In the center of the battlefield you will be able to see the capital itself, and that is where the fighting takes place. That spot is like a winner stays on position. One player may be there at a time and players in other alliances may attack him as much as they wish. Fights in the capital battle do not effect the army cooldown, but only have the 10 second cooldown of the capital area. Each player who attacks the "king of the hill" as they are referred to - will take them on in a one on one, if they are victorius; they will take their spot as the king of the hill. At 11AM, when the capital battle is over, the alliance with a player in that position will take command of the capital for that day. At 10AM the following day the Capital will be reset and the alliance must have a player in the king of the hill position at 11AM again to take the Capital for another day.
Every member of the alliance who resides in a city where their alliance is in control of the Capital will have access to the Capital Mine and Farm. The Capital Mine and Farm may be used up to 5 times each, every day, with a cooldown of two minutes after each collection. In every city the mine will give 500 gold per the player's Town Hall level per collection. And the Farm will give 300 per level, per collection, for a potential 250,000 gold and 150,000 food per day if the player were a level 100.