Ring of Swords
As Ursula K. Le Guin writes in her new introduction: "Having recently brought their own competitive, feud-ridden society into a fragile balance of peace, the Hwarhath have been facing an unexpected problem: the lack of enemies. Given the apparently innate male propensity for finding pretexts to fight, and the fact that their men were all trained as warriors, the women running things at home make sure the men stay out in space protecting the home planet. The drawback is that there seems to be nobody to protect it from. So, when in the vastness of space they finally stumble into another intelligent species, they rejoice. Enemies! At last!, And those enemies? Humans, of course. And yet, Ring of Swords is a novel "not about fighting a war, but about trying not to." Book jacket.