Trireme is only in phase 2 and quinquereme in phase 3, it is fair that bireme is already in a village phase.
I think it would be interesting to be possible water wars in the first phase of the game. Some maps like oasis or new maps by @badosu would be quite interesting.
Bireme is little used today because it is available with trireme, this patch should help with that. Also encourage more actions early in the game instead of boom.