Declaring War – it sounds scary, but it’s fairly easy.
Find the alliance you want to declare war on. View that alliance page, and tap the Diplomacy tab (the third icon that looks like a scroll).
Empire: Four Kingdoms – Declaring War
Tap the “Declare War” option. VOILA! You just started a war.
Here is the message your alliance mates see when war is declared.
Empire: Four Kingdoms – Alliance Notification
Now your alliance will get the Alliance Bonuses that only apply to war, such as the Attack Travel Speed, and the Wartime Looting Bonus.
Be warned… starting a war usually means that outposts and villages are fair game… as is mass attacks, double and triple hits, and lots of sabotage.