Gazebos? Really?
I bet the Marines don't have any gazebos.
As to those lost troops could it be folks who have left the service but the computer systems haven't caught up to that yet?
That is they're not deployed anywhere but they still appear on a unit's roster but obviously aren't stationed there.
I was in Vietnam when the Army still used IBM punch cards as the computer storage medium. Every unit, at the company level, had to submit a morning report that detailed where every person assigned to that unit was. If someone was on leave, he was reported as on leave. If someone was in the hospital, he was reported as in the hospital (and the hospital would be reporting him as in their care). If a person was absent on TDY, he was reported as on TDY. And if we didn't know where someone was, he was reported as AWOL. We had a few of those (AWOLs) when I was stationed at Edgewood Arsenal.
One of them I tracked down by telephone. He was a younger soldier, a draftee, who came from a somewhat well-to-do family and had an atitude that the rules didn't apply to him. One Saturday morning he wasn't there for morning assembly and roll call. I had my suspicions, so I tried to call his family's home. Hmmm ... unlisted number. This was long before the breakup of AT&T ("Ma Bell") and there were still live operators in the system, so I dialed 'O.' I told the operator this was an official call from Headquarters Company, 4th Battalion, First Artillery Regiment, United States Army, and that it was essential for us to contact [___] at such-and-such address. I asked her to put the call through and ask whoever answered to take the call.
It worked. The father came on the line, and admitted that sonny boy was at home. I told him his son was AWOL and that if he didn't get his ass back to the post ASAP the MPs would be making a visit. Sonny boy showed up in time for Sunday roll call, and the First sergeant didn't say anything more (publicly, but I believe there was a rather terse meeting between sonny boy and the CO and Top Sergeant).
We had another one we suspected had gone off to spend time with his girlfriend in Baltimore. Top sent me and the duty driver to her address. I went around to the back yard. The driver knocked on the front door, and I caught Private Goober as he came running out the back door. Oops.
Troops did occasionaly get lost in the system, but in general someone had to really screw the pooch for it to happen for more than a day or two. And this was decades before modern computer networks.