In fact, Campbell / Blackwatch tartan is universal precisely because it was used by the military. During the Highland Proscriptions, the only tartans woven were those of military regiments, and the only kilts worn were likewise.

Those who had taken the king's shilling were more common than you'd think, and they brought their kilts home with them, so that when the Proscriptions were lifted, there were a lot of fellows left with kilts in that tartan.

At least, that's my understanding of it.