There was a section on the cRPG website with a list of batatles, arranged by the time in which they would take place, and the server where it was happening. If you wanted to join a battle, you would click on the battle, and ask the commander of whatever side you wished to join.
If accepted, you waited for your time-slot. At, for example, 1600 you would join the strategus server and help your respective team win. It's TDM style, done with tickets. Team one might have 1000 "soldiers" (tickets), while team two might only have 100 "soldiers". The only people participing in the battle, however, would be the ones who joined via the cRPG website. The 1000 soldiers/tickets are not actual npc's, but rather, respawns.
I only participated in one or two battles, since I wasn't in a clan, nor did I really have the time to do it. If your clan's in a battle at 1400, and you've got work or class then, you miss the fight.