Supercell has fully detailed and explained the process of Clan Wars, the newly announced feature in Clash of Clans. As the name suggests, a clan war is a “strategic battle” between two clans. It takes place over the course of two days — a preparation day and a battle day — and provides the winning clan with a large loot bonus; although, every clan member who makes successful attacks during a clan war also earns some bonus loot.
Clan wars can only be started by leaders or co-leaders. Once started, the game will search for an opponent clan of similar strength. Strength isn’t determined by the number of trophies, but instead by each member’s attacking power (troops, army camp capacity, spells and heroes) and defensive strength (defense buildings, walls, traps and heroes).
It’s important to note that your village is always safe from clan war attacks because clan wars are fought in a different area entirely — the war zone. In the war zone, you prepare and attack “war bases” instead of regular villages; therefore, your village’s resources, trophies, and shield are never at risk.
Clan wars matchmaking will only match clans of similar sizes and both clans will always have the same number of war bases. As a result, a few members (between 1-4 per clan) may be put into a spectator mode to even out team sizes. Spectators will always be the clan member will the lowest trophy count in their respective clan.
Once a clan war begins, you will see The War Map, a map of the war zone where clan wars take place. Friendly territories will always be on the left, with the enemy clan on the right. Every town hall on the war map represents a war base.
Your war base is similar to your regular village, except that your war base will not generate resources. Buildings in your war base can’t be directly upgraded or rearranged, as it merely mimics the arrangement and highest completed upgrade levels of your village during preparation day. War bases also never need to have their traps rearmed, defenses reloaded or heroes healed, as they are always ready. The clan castle in your war base must be filled separately from the one in your village.
By tapping on a town hall you can view more information about that play, scout, donate troops, or attack. Of course, these actions will depend on what phase of the war you are in.