Fallen attacked the village from HRE so they could get control of it. I'm assuming they wanted to transfer ownership to another Fallen member, and the only way to do that is to attack their own village.
It's also possible they did this as a stalling tactic to get more people heading that direction to reinforce. This is a known issue and the dev's have acknowledged it. But like the issue where defenders lose all their gear they have equipped if they win a battle, it's a game breaking issue that completely fucks over strategus. And like any game breaking issue, has been unresolved since it was reported to the devs.
Go Devs!! YeaH!!!!!
More dedicated developers could have literally taken the concept from this game and created a completely new game on a different game engine and marketed it to publishers and selling it for 15 bucks a pop by now. C-RPG and Strategus have unlimited potential and a completely open market share if they were interested. Hell maybe that's why c-rpg and strategus have been so neglected, maybe they are creating a game that will make them some money.