The Return of Retief — Keith Laumer

PLANET AFTER PLANET FELL TO THE REE

A vast and powerful race, the Ree needed breeding room for an ever-increasing population--and their expansion plans took no account of human territory. The farmers and miners of Tip Space were helpless against the Ree invasion. Still the Terran diplomats dithered, holding back the Navy hoping for a truce.

Retief, already on probation for undiplomatic behavior, earned himself the assignment of parleying with the Ree when he urged force against them. A suicide mission? erhaps...but Retief is Retief.