He was particularly known for his studies of Swedish history, and his introduction of the concept of a Military Revolution in early modern Europe.
This theory holds that certain changes in military tactics and technology led to a revolutionary new method of waging war that made combat more decisive.
In addition, he proposed the concept of a 'military revolution' in the early modern Europe - an idea that, with modification, is still used by historians.
Roberts also wrote translated the poet Birger Sjöberg and Sweden's bard Carl Michael Bellman into English,[2] which he published himself.
Jeremy Black, writing in History Today, comments that "Few subjects are identified so closely with one man as English-language scholarship on early-modern Sweden and Michael Roberts.