Rome: Total War. (Questions)?

If your allies army is nearby your army when the battle starts, they will enter the battlefield on the far end just like your other army would as he mentioned above. But unfortunately there is no way to get an ally to travel any distance to help you if they are not already right by you. if your being "chased" you could always run to where an ally army is. as far as SPQR, you will have to have a lot of territories and lots of armies. I don't know how many exactly but your empire has to be pretty large. and you also have to have a good public standing. but larger army= less public standing needed.