I'm looking for the titles of a military space opera trilogy (I think) that was more or less directly copied from an earlier series or a non-SF military series.

My memory is quite vague but I think it was published quite a few years after Dune, maybe in the 1980s or 1990s. It was a fairly big best seller in the UK at least, before it was identified as being plagiarised from the earlier series.

I think the original was based around the time of the second world war - possibly in the Soviet Union?

I think there was a court case resulting in a small amount in royalties being paid to the original author.

I'd be interested to know the original books' titles and author as well as any other details.