Lanefan
Victoria Rules
What happened to "Defense of any charge unto death", "Battle is the source of all personal glory", and "Death before dishonour, death before defeat"? That's from the old code of chivalry - it had a bunch of other stuff too - and would seem to apply here. Or are Paladins not considered chivalrous any more?Not necessarily. By which I mean an oath could theoretically exist which carries tenants that do run counter to retreating with your party, but none of the oath tenets that I've seen thus far do so.
The closest it gets is the Oath of Devotion tenant of courage, which says "Never fear to act, though caution is wise." That is more support for a wise retreat than it is for foolhardy self-sacrifice, though.

Lan-"I'm really surprised they don't have at least an Oath of Chivalry to cover this sort of thing"-efan