I've heard that more than once in my history classes....but then again...i was a History major in college 
Interesting. Over the years I've gone through about 30 theories of history, the military being one, though out of favor for about a generation. My two favorites are the Pirean thesis (that western civilization reached its pinnacle in 1200 and has been downhill since) and the infectious disease theory.
One of my favorite historical figures, Helen Keller, subscribed to the great man theory. She thought George Washington and Nicolai Lenin were the greatest.
About thirty years ago there was a book about the 100 most influential people, based on a combination of how many people they affected and how deeply they affected them. Mohammad was first, Newton second, and Jesus third. It was a great analytical tool for discussion.