Special Activities Division was created in 1947.
Honestly? It would probably be the Special Activities Division of the CIA, rather than any actual military unit.
You can join the CIA without military experience but the Special Activities Division is a highly trained division, most of the SAD agents are recruited from Army Delta or Navy SEALs, so it's very unlikely, I am not saying that is impossible just because there isn't much information about the recruiting process, but I can't imagine a inexperienced person fighting alongside these high skilled soldiers, if there is any position for non military is probably in supporting position like intelligence analyst.
Pansy Division was created in 1991.
Norris Division was created in 1974.
The Yellow Division was created in 1954.
Canadian Division was created in 1926.
Scottish Division was created in 1968.
Barisal Division was created in 1797.
Division Élite was created in 1926.
Sin Division was created in 2006.
Daylight Division was created in 2009.
Cassini's Division was created in 2001.