PATROL BASE DIAMOND, Vietnam — It was a long day for Companies A and D of the 2nd Bn., 27th Inf. It began at 4:30 a.m. and ended at dawn Tuesday. When it did, a lot of people were dead.

Pulling themselves out of their tiny bunkers before the sun had come up, the 25th Inf. Div, soldiers began their five-mile move northward from Patrol Base Diamond II to what was to be Patrol Base Diamond III, when they built it.

By seven o'clock A Co. had arrived at a flat plain of dried up rice paddies. The nearest treeline to the northeast was in Cambodia.

New bunkers went up. A 120mm and three 81mm mortars were moved in, joined by a pair of howitzers, A single strand of concertina wire was strung around a two-foot high dirt wall around the camp.

Meanwhile, D Co, turned Diamond II back into the nothingness that it had been, leaving only scattered stakes that were buried too deep to be dug out. At 6:45 p.m. they left and joined A Co. an hour later.

By 9 p.m. Diamond III was 80 per cent completed — 16 bunkered fighting positions, a tactical operations center, two artillery and mortar emplacements. Three listening posts had been set out to the north, east and west.

There was no moon and the men settled down.

"Everybody was expecting something . . . . they always try to catch you with your drawers down . . . . they always hit us on the first night," one soldier said. It came at a few minutes past three Tuesday morning.

Movement was picked up on the radar. The artillery blasted out. Movement was sighted by soldiers in the west listening post. Illumination rounds were fired.

Just as they lit up the night, the mortars and rocket-propelled grenades began to hit Diamond III. In the next two hours, the camp was riddled with perhaps 800 shells.

"Before we went out, I told my squad I was sure we were going to be hit, but I never expected that many mortars," said Spec. 4 Robert Morrison, squad leader at the west listening post.

"After they started, I called in to the command post and got permission to get back in when they stopped. When they did, we grabbed as much gear as we could and took off. We spotted a machine gun position about 100 yards off to our side as we came in."

But it was a half-hour before the pause came. Meanwhile, shells had ripped into communications lines, cutting off the east listening post.

Then came the ground attack — one battalion from the east and one from the west. GIs rushed out from bunkers to drive back the enemy approaching under cover of yet unflattened rice-paddy dikes surrounding Diamond III. And then the mortars began again:

"They kept their distance on the ground," said Spec. 4 Drew Peterson, a rifleman of D Co. "A bangalore blew a hole in the wire, but they never tried to get closer than 20 to 30 yards.

"But they knew we'd be out there and they kept dropping in mortars."

But the GIs had known the fight was coming; they had spent the day getting ready for it and they fought back. When communications lines went out, they ran messages back and forth. Artillery was lowered to fire straight on at the enemy. Helicopter gunships, more artillery and fighter-bombers moved in to back the infantrymen.

At 5:15 the enemy began to draw back. By dawn the shooting was over. One of the 81mm mortars had taken a direct hit with an RPG. The four soldiers manning it were dead. The east listening post had been overrun. Seven of the eight soldiers at it were dead. Two other Americans had died elsewhere in the battle.

Surrounding Diamond III were 198 dead North Vietnamese.

The sun was up. The long day had ended for Companies A and D. But the next day had already begun.