No, Casper Van Dien did not serve in the military. He is an actor known for his roles in films such as "Starship Troopers" and "Sleepy Hollow." Van Dien's acting career began in the early 1990s, and he has since appeared in numerous films and television shows. He has not served in any branch of the military.
Mastering the Casper Van Dien Universe: A Quiz on the Starship Trooper's Stellar Career