The Portuguese, for the most part.
Actually it was a great (zany) assignment, which to fully appreciate you'd have to read Joseph Heller's Catch-22.
But, in brief, it was (and is) an Air Force base with 1800 personnel but only one plane, a T-39 used for two mail runs a week to Spain. A naval air station with 1200 personnel and some 30 aircraft, but no ships. An Army transportation unit comprised of 800 personnel, no artillery or armor, a few 4X's and 6X's and a couple dozen ships. And finally, 50 marines with only M16's standing guard over an ammo dump belonging to the Navy.
Four branches of service on a base roughly 3 x 5 miles on an island measuring 11 x 18 miles, situated 880 miles off the mainland. Military discipline was entirely non-existent; no saluting due to the difficulty in recognizing four brands of insignia. The one exception being the AF brigadier, since everyone knew a star when they saw one. Oh, and one AF captain who was a real A-hole, having begun life as a slick-sleeve, risen through the ranks and went to OCS. But apart from that pair, life was very much like Bill Murray's unit in Stripes.
I'll leave it to you to picture the scene at the Service Club during the six-hour Happy Hour sessions on Friday and Saturday nights.
The only level spot on the island: