We started the first flight line headed northbound. Our camera would be the infrared scanner which recorded a mile-wide swath directly beneath our RF-4C reconnaissance jet. We roared along at about 480 knots at an altitude of 1000 feet above the relatively level terrain. I was sure that this mission would be a "piece of cake" and wholly uneventful. Boy, was I wrong.
The excitement began with the sudden appearance of a rocket or
mortar shell's bright red trail arching high over us from east
to west. We flew beneath the arcing light, well clear of its
trajectory perhaps 1500 feet above us. We weren't sure at first
whether it was ground to ground fire or someone shooting at us.
Quickly we double-checked to be sure our navigation and
anti-collision lights were turned off and not an easy target for
"bad guys" on the ground. Only the roar of our twin jet engines
disclosed our position and path.
We turned back to the south after completing the initial
northbound flight line. I checked to be sure that we were on the
proper course and verified that our cameras were running. About
half way along the flight line we saw two more high arching
tracers, brilliant red streaks close together and once more
emanating from the east of our route. Still we couldn't
determine whether they were rockets, mortars or artillery.
With relief we noted again that the projectiles were well above us.

On our second northbound leg we found ourselves fully between westbound tracers and even more eastbound response firings. Most were bright red, but a few seemed to be yellowish. At one time there were at least a dozen streaks overhead, bright with the exchanging volleys of what was becoming a fierce duel. We considered aborting our mission and getting the heck out of there, but decided not to give up yet. This must indeed be important terrain and our mission took on greater significance. As long as we were apparently not the object of the gunners, good guys or bad guys. We elected to continue, at least until the tracers got closer.
Just to be sure that anyone taking an interest in us would find us harder to hit, we pushed up the throttles and accelerated to about 540 knots. Luckily we had plenty of fuel and were not very far from our home base.
Though we were quite concerned, excited and maybe a little scared, we were determined to complete the mission. But we both agreed that it sure was a great fireworks show. Just as soon as we completed the final leg, one to the south, we hastily left the area and climbed to a safe 25,000 foot cruise altitude back to Saigon.
Not surprisingly, we never did get an explanation from the intelligence folks about what we were supposed to be photographing or who was doing what with all that firing. If our mission was important, we never knew why.