Is it possible to have served in all branches of the military during the Vietnam Era?

I'm not sure that it would be possible considering the terms of the draft at that time. When someone was drafted during the Vietnam era there was a two year obligation attached. Now considering the Vietnam conflict was from Aug 1964 to May 1975 (officially) that gives a person less than nine years to have served in every branch. Not saying that it could not be completed but it does sound like it would be difficult to pull off. Now if the person joined without the draft the term of service varied. If they did choose a combat role such as Infantry and spent a year in the jungle they could theoretically extend for an additional six months. Which would mean that upon the completion of the six months they could be discharged thereby allowing them to depart that service (giving them just 21 to 22 months of service) and join into another one. But then again this would be somewhat of a difficult thing if there were any underlying injuries upon discharge. I would just take with a grain of salt.

It is technically possible. My dad went through USAF basic in 1968. His TIs were prior service Marines. One of the guys in his flight said he had 'been in the Army' asked the drill if he could wear his decorations from the Army. They formed up for church on Sunday in Class As with a Silver Star and CIB recipient who had more decorations than some of the drills. Many USAF communications airmen were involuntarily transferred from the Navy in the late 1950s, forget why. My JROTC NCO was one of them. I think your path would likely have to start with the Marines, as they do not recognize anyone else's initial entry training.

In the recent era, I have a classmate from college that served AD Navy, went to college, joined the Army National Guard, transferred to the Air National Guard and retired from the ANG.

I met an Air Force Lieutenant Colonel in 1988 that had been in all branches but the Navy, he was a Marine in Korea, an Army Infantryman (with a Glider Badge!), and earns a commission in the Air Force.

My battle buddy in the advanced course was a Marine in 1982, an Army Cobra Mechanic in 1984/5, and commissioned in 1994 serving as a Tanker and a Transportation Officer. knew an Army Warrant that went High School to Flight School, then branch transferred to the USCG as a commissioned pilot.

While it may be possible, the side effect would be, unless there is a commission or warrant appointment in there somewhere, this person would be a career E5. Perhaps they were drafted into their first branch (Marines/Army) then selected the other three. Perhaps a pit stop through the National Guard in between.

SPC Diana D. I can see supporting all the branches, but actually serving in all the branches is hard to believe, although, anything is possible.