Has this series been released on DVD?

I'm not sure if "20th Century Battlefields" has been released on DVD. However, you and your students may be interested in a similar series produced by Dan and Peter Snow, called "Battlefield: Britain". It came out a year or two earlier. The episodes are the same format as "20th Century", but the production values are better, in my opinion. The series focuses on battles involving the British. It spans pre-dark ages battles to the Battle of Britain in World War 2. I found the DVD set at my local library. It was great. Plus, it was shot in 16x9, so it fills up widescreen televisions.