[WalterBright]

Sounds a lot like the Italian mercenary armies in the middle ages, where they mostly maneuvered for advantage rather than fought. Being mercenaries, they had little interest in dying for their employer's cause.

[raincom]

Another example: https://en.wikipedia.org/wiki/Live_and_let_live_(World_War_I...

This example was discussed in Robert Axelrod's "The Evolution of Cooperation".