I am playing with UK, quite well. I achieved to conquer Germany with the first Field Marshalls (FM) I had. Once I began attackin USSR suddenly they collapsed returning to be Major Generals. I put some others, and in the second year of attacking USSR the new ones collapsed again. Now attacking Japan they have collapsed again. When I say collapsed I mean that a FM with a skill of 1, 2 or 3, suddenly converts himself in a Major, or Lt. with no more than 1 or 2 levels. His profile maintains all of their victories. No problem at all with my UK FM's. Why is this?