But after he graduated from college in the spring of 1968, making him eligible to be drafted and sent to Vietnam, he received a diagnosis that would change his path: bone spurs in his heels. The diagnosis resulted in a coveted 1-Y medical deferment that fall, exempting him from military service as the United States was undertaking huge troop deployments to Southeast Asia, inducting about 300,000 men into the military that year. The deferment was one of five Mr. Trump received during Vietnam. The others were for education.

https://www.nytimes.com/2016/08/02/us/politics/donald-trump-draft-record.html