After the holders of the Elements of Harmony passed away, a rift in Equestria formed. Two different ideals formed, as well as followers of those ideals. The Orthodoxy, believers that the Elements should be passed down to their closest of kin. Then there's the Anti-Elementalists, who believe ponies shouldn't rely on the elements anymore. At first both sides were complacent with standing by, so long as they weren't aggressed by the other side. However, known Anti-Elementalists were often publicly attacked by neighbors, and even the politicians hated them. Eventually, Princess Celestia reached an breaking point, and attacked an Anti-Elementalist settlement. Soon, ponies were fighting in a war they didn't want to have. This will be WWII esque warfare, and you will be able to be on either side as an soldier or non-combatant role. If you have and questions about it, ask away in an PM or on this thread.