Wasn’t that just 2 guys? You make it sound like a military operation.
They were the last two guys. There were many who trickled in over those 4 years.
I’m thinking near the end of that time period (say 1947-49) there was really no USA military need for Iwo Jima. It might not have had anyone living on it except undiscovered Japanese soldiers and a couple of caretakers.