what if we assume that camp pendleton and its military personnel were transported by advanced human technology as a last ditch effort to safe a remnent of humanity before some advance alien race completely exterminates the human race.
Appearing from a time bubble from their apocalyptic future a handful of future military techs install and activate a temporal field around of camp pendleton, minutes/seconds before the alien attack is begun and pendleton is destroyed by their first initial bombardment. they activate a time shift only to have timed their jump off by a few secs the energy blast and the temporal field interact causing coordinates to become altered and sending camp pendleton into the out skirts of the roman empire.
the blast caused the tech to overload and be destroyed killing all but one tech, realizing instead of sending the base into a remote corner of the united states some 100,000 yrs. he has send them into the height of the roman empire running the risk of horribly altering the time stream. he now has to find the base commander and inform him of the future threat.
1. realizing altering the time stream is far better then complete planetary annihilation he searches for the base commander. their goal is to prepare humanity with future tech and knowledge to advance the world or the military base and their future ancestors sufficiently to fend of the alien invasion.
the problem is the local tribes peasants have started spreading rumors about gods, demon , strange foreigners invading the country.
the roman senate has sent troops, scouts to confirm the reports of the locals.
due to lack of communication negotiations break down and the war begins.
mission of the base is not complete annihilation or even the removal of ceaser they are needed in or order to help spread human advancement to fend off the alien invasion. in order to do that they need to defeat the roman armies.