If you just want battle with objectives, get someone to host a "defend and destroy" (I think that's what it's called) server. That's a native gamemode that was popular for a while in the warband beta and has never been seen since. It's just battle, but one team has to defend a catapult and a trebuchet, while the other team has to destroy them. Rounds are won by timer, an entire team getting killed, or both objectives being destroyed. The objectives kinda work like the doors in siege, you just hit em to damage them and their HP is scaled by the amount of players.