Damocles Gulf Crusade

The Damocles Crusade, also called the Damocles Gulf Crusade was a major conflict fought between the Imperium of Man and Tau Empire around the Damocles Gulf region of the Eastern Fringe. It was the first military conflict between the Imperium and T'au.
The conflict essentially ended in a stalemate in late 745.M41, as the Imperium was forced to conclude its military offensive early to deal with the encroaching Tyranid threat while the T'au sought to begin diplomatic negotiations with the Imperium to show humanity the benefits to be had by accepting the Greater Good.