Petain was Commander and Chief of the French forces in WWI, prime-minister of France during WWII and leader of Vichy France. So not only a major leader in both

Petain was Commander and Chief of the French forces in WWI, prime-minister of France during WWII and leader of Vichy France. So not only a major leader in both wars, but in the second war he held high office on both sides! (and FDR was Asst Sec of the Navy in WWI if you count that as a high office)