T. R. Fehrenbach (in This Kind of War) tells the story of a company given the mission of covering the valley beyond Heartbreak Ridge:
By day Busbey could cover the valley by fire, but at night it was a matter of setting up ambush patrols near the stream and on the fingers of the covering ridge to prevent the enemy from mining the valley floor and stream bed.
[...]
Several of his men with a light machine gun manned by an assistant gunner who had never fired in combat were sitting close by the stream. They heard the stealthy noises of approaching men, and through the dark were able to make out a mining patrol, 2 NKPA officers, and half a dozen enlisted men carrying AT mines.
“Wait till they’re closer,” the machine gunner whispered.
To fully load a round into the chamber of a light machine gun, the bolt must be pulled to the rear and released twice. The assistant gunner, who had pulled the bolt back once, thought the gun full loaded — until the pressure on the trigger produced only a terrifyingly loud click.
By the time the patrol figured out what was wrong, the North Koreans were six feet away. The first shot tore off the top of an NKPA lieutenant’s head. Swiveling the gun rapidly, the blond young man who had waited just a bit longer than he had intended cut down all of the surprised unfortunates before they could escape.
Next morning Major General Claude Ferenbaugh, the division commander, who visited front positions regularly, was shown the stiff and blasted Korean corpses. “By God,” Ferenbaugh said, “I get these reports all the time, but this is the first time anyone has had the bodies to prove it!”
He decorated the blond gunner before he left.
Now there was no offensive action taken against the enemy — but an army could not sit still. It had to patrol, even as the enemy had to patrol, to keep contact, to see what the other side was doing, and to attempt to keep the other side honest.
It was this patrol action, this continual flirting with danger and death, for reasons many of the enlisted men thought flimsy, that soldiers all across the Eighth Army’s line came to hate. But there was no help for it.
And while the front was still, except for patrols, there was the shelling. The enemy, who had to bring his precious ammunition under air attack over many miles, did not care to waste it. But he was not loath to shoot it, if he had a target.
One of Busbey’s platoon leaders, Jack Sadler, was restive at the inactivity. “How about letting me snipe at them over there with my 75mm recoilless?”
“Hell, you’ll make ’em mad, Jack,” Busbey told him.
“Aw, just one round, anyway —”
Sadler fired one round at the enemy lines, with indeterminate effect.
Then, immediately, the enemy shelled his platoon, heavily. Two of Sadler’s men were killed — and forever afterward Sadler held himself responsible. After that, a sort of gentlemen’s agreement held — each side left the other alone during the day.
It was a weird war now, not so dangerous, but more frustrating than ever.