I see I posted my duty title in an earlier post a few years ago: Chief of Targets, 432nd Reconnaissance Technical Squadron, Udorn Royal Thai Air Force Base.
I was running a team of photo interpreters and target analysts who were reading out drone imagery (from the Ryan Firebee, or "Bug") and reporting our findings to various headquarters. We'd been watching the NVA coming south for some time. The Vietnamese Marines and Airborne troops would be holding up fairly well, but the ARVN would usually collapse and head for the hills, leaving the Marines and Airborne with exposed flanks, so they'd have to fall back and re-establish a line of defense further south. We also tracked an SA-2 coming south on the Ho Chi Minh Trail, knowing that when it came within range of the Saigon airspace it would be lights out. The NVA got there first, but not by much.
The image of the T-54 pushing through the gates of the Presidential Palace is well known, but somewhere I still have an image of another T-54 parked across the street from the main gate of Tan Son Nhut (where I spent my first SEA tour, in 71-72). That tank was parked directly in front of the "Magic Fingers" massage parlor.
A few weeks earlier, we had built photo maps for the US Marines going into Phnom Penh for Operation Eagle Pull and a few weeks later we were looking for the crew of SS Mayaguez and trying to locate the guns in the tree-line on Koh Tang Island.
When I think of those days, I think of the very junior guys in my branch (mostly E-3 and E-4), who worked under tremendous pressure and produced top notch analysis and reporting.