Oh, the Imperium was also slaughtering the Tau in space combat. It's once they started putting boots on the ground they ran into trouble.<br/><br/>Despite all their neat toys, the Tau still aren't on par with the other factions for warships. Once you get on the ground though... the tech advantage really comes into play and the Imperium has never committed enough troops to truly take advantage of numbers. The practice of assimilation instead of extermination also gives them a major advantage. The Kroot and Vespid both are extremely good at what they do, the Kroot in particular are good enough they stalled a<em>Tyranid</em>invasion in the jungle. The area that<em>everyone </em>else would want to stay as far away from as possible when dealing with Tyranids.