The stronghold missions are supposed to be hard, as that will eliminate that race from the game. Guardsman are pitifully weak in small numbers against stronger infantry, especially if you have flamers or heavy bolters. This obviously suits Tau better than it suits IG, as Tau infantry is generally stronger and more varied.Īlso, of course you can bumrush IG at the start with Sisters (or most other races). Sometimes the AI never techs up for some reason, I guess due to variation in AI strategies that it can employ, and this leads to them only rushing with infantry. IG untis don't do well when doing this and tend to get slaughtered. Tau is much easier for the AI to handle as their units tend to do well when massed and ordered to rush attack in large mixed groups. The AI isn't really cut out for figuring stuff out like that.
For example, one of IGs strongest abilities is to use the commissars execute among large groups of guardsman or near heavy weapons teams. IG AI is typically weak (although sometimes it can be nasty), as IG requires some tactics to make work.