The conflict started when the Yautja's constant habit of allowing their Hunter-Killers to hunt on any planet, and kill any individual, led to a massive outcry to the League demanding action. Despite the public opinion, the League did nothing, as they did not want to start a war. However, Gravespeare decided that it was time to prove the worth of his hive and gain favour of the League at the same time...
The Yautja had recently conquered a planet known as Skirrid, and the Gravespeare used Flood Dispersal Pods to distribute Flood Infection Forms amongst the colony. Despite Initially dealing quite well with the infestation, the Yautja eventually succumbed to overwhelming numbers. The carelessness of many of the Yautja warriors led to their infection. Yautja warriors remove their masks when they engage in hand-to-hand combat with their foes, and their underestimation of the nature of the Flood led to many of them simply being overwhelmed and infected.
Outnumbered and quickly becoming surrounded, the Yautja forces were quickly defeated. Fatally, they did not heed the advice of the many experts sent to aid them by SUCAS, and their shipyards were overtaken by the Flood. When a Yautja fleet arrived to reinforce the planet Skirrid, they found the planet a hive, and the ships that once defended it were completely overtaken. The entire new fleet was then overtaken and infected, the commanders killed and their bodies ejected into space by the Flood forms. The Yautja decided not to send any more fleets to retake Skirrid, and peace talks between the League and the Yautja began. However, Gravespeare was never asked to relinquish control of Skirrid, only that the ships he infected be crashed on the surface. Skirrid is, however, still a commonly visited planet as a Galactic Trade Route runs through there, so in essence the spirit of Skirrid lived on even after the war.