Does only five survivors from a whole Century sound realistic?

[Jason Micallef]

I am writing a novel, and there is an opening scene in which a detatchment of an Auxillairy Century is accidently abandoned, and left to fight against impossible odds. I decided to have only around five men survive before help arrives. These five comrades, all from different conteburniums, are the main characters of the story. 
I just want to see if anyone thinks such a small number of well trained men surviving sounds realistic? I often debate with myself if this sounds plausible or simply too far fetched?

Any suggestions? Thoughts?

[Steven James]

Depending on how it is done, I see no problem in five men surviving. The auxiliary century could be defeated, and the men routing in all directions, with the five surviving men individually crossing paths later as each one tries to reach safety. It could be that the auxiliary century was holding a small mountain pass, was defeated, with the scattered survivors trying to make their way to the main body which was defending another valley pass or something. The five men could then unite and try to set out to warn the main body that the enemy was undertaking a flanking move in force on the main body.

[dadlamassu]

It would depend on the tactical situation that has reduced the Century to 5 survivors.  It may be a night assault by the enemy and the 5 men either escape or are knocked out and survive.  Though the escape might be more likely with several others being chased down by the enemy and these 5 escape and end up together at a water source or return to the camp to see what they can glean by way of supplies.  

They may, for some reason, have been placed out on guard on the side away from the main action, or given the task of guarding the mules, wagon, cart or whatever.  One of the 5 may be the tesserarius (I assume the auxiliary centuries had them but cannot remember a source) who was doing his rounds or giving the guard their orders.  Thus giving the chance for a leader and a power struggle between the characters.   

After falling foul of the Centurion they were designated to guard a cart full of kit.  On the march the cart damaged a wheel or axle and they were left behind and had to repair it.  By the time they reached the column/marching camp the action/ambush was over.