From the Archives - Corcoran the Mortarman: Company Mortars and Ruthless Concentrations of Fire
by Brendan McBreen
Editor’s Note: This article was originally published in March 2022. I recently spoke with an active duty Major General and his main message to me was: Be prepared to fight at odds… We’ve done it before and we can do it again. The following story is one such example.
“Marines!” The captain held up his hand for silence. “We have a guest speaker for this afternoon’s PME.
“My grandfather, Sergeant Thomas Corcoran, fought in Korea with 7th Marines back in 1950.” The captain smiled at the old man next to him.
“I went to the office supply store yesterday and had this map enlarged.” He pointed to an oversized poster taped to the wall. “It’s from U.S. Marine Operations in Korea. I’ve asked my grandfather to tell one story, about one night, on one hill, and the lessons he learned there.”
The old man looked at the faces of his audience. The officers of the battalion looked back, expectantly. Sergeant Corcoran was wiry, white-haired, and frail, but when he spoke, his voice was precise: “I was a mortarman."
“I spent nine months in combat,” he said. “In the first week of November, we were south of Sudong, moving to Chosin. In this valley,” he touched the map, “the Chinese attacked us for two days. Two regiments of the People’s Liberation Army surrounded and cut off most units of the 7th Marines. I was here.”
He put his finger on the map. “Hill 698.” Yellow post-it notes on the map showed a company position—a perimeter defense of three platoons, a company headquarters, machineguns, and a 60mm mortar section. Other red stickies showed enemy units.
“At midnight on the first night, all hell broke loose. Under illumination shells from 3/11, we saw hundreds of enemy moving towards us in the shadows. We heard the firefights from distant units. The whole valley was under attack.
“Our mortar section was commanded by Mister Conner. He had studied the folds in the ground and picked out two enemy avenues of approach, where their assault might come. We laid our tubes on this draw to the northwest.” He pointed. “Interlocking machineguns also covered these approaches. We didn’t fire any adjustment rounds because they were watching us. Remember. The Chinese were a real army. We knew we would be killed up there if we weren’t good.
“The company had carried one-hundred twenty rounds up the hill and by 0400, during the enemy’s third assault, we had shot them all.
“The first assault was the worst. They came at us with everything they had, firing, screaming, and blowing bugles. We gritted our teeth and waited: ‘Hold your fire!’ I was shaking.
“When their assault was 400 meters away, the CO opened fire. Everything, all at once. Overwhelming fire concentrated at the commander’s direction. The enemy in the draw was bunched up and vulnerable and the slaughter was terrible.
“In two minutes, we fired twenty rounds a tube, half our ammunition. Mister Conner called out the corrections: ‘Right! Five-zero! Drop one-zero-zero!’ “They came back twice more, but not like the first. By the third assault, Mister Conner said: ‘Shoot it all! We’re not carrying it back down!’ I thought we were going to be overrun.
“At dawn, the Corsairs flew up the valley with close air support. We sent Marines down for ammunition—the enemy still held the road. For two days, we fought and held. The regiment eventually counted over 600 enemy dead.
“We carried Lieutenant Conner off the hill on the third morning...” The old man paused, remembering, and the room was quiet, respectful of his story.
Mortars
“Let’s talk about mortars,” Corcoran said, starting up again. “In nine months of combat, we probably fired four thousand rounds—day, night, hot, cold, mountains and valleys—so we got pretty good. Here’s what I learned about mortars.
“Shoot one target at a time.” He held up an index finger. “One important target that supports the company commander’s plan. There’s always going to be enemy probes, patrols, and infiltrators, and the platoons will always beg for fires, but you can’t fire unless the CO says so.
“Shoot overwhelming fires. Put a lot of rounds, all at once, on one important target. Suppression and neutralization need a lot of shrapnel to be effective.
“Shoot mortar targets. Shoot at infantry, moving in the open, or hiding behind hills. Break up enemy formations in assembly areas and draws. Don’t fire at buildings, bunkers or tanks. The mortar is an area suppression weapon.
“Don’t waste ammunition. You can only carry so many rounds. Divide ammunition into thirds: three targets, thirty rounds each. You can’t fire at everything. Single rounds are meaningless. No harassment fire. No platoon targets. No illum.
“Plan the company attack. You only have minutes of suppression. Don’t fire early. When the support-by-fire opens up, you get thirty rounds in two minutes. The assault element needs to understand that. Mortars have two tasks: suppressing enemy positions during the attack and neutralizing enemy assaults during the defense. Suppression is not destruction.”
Questions
“Okay.” Corcoran took a deep breath. “Bobby told me not to talk too long. Are there any questions?”
Around the room, officers shifted in their seats. A lieutenant spoke up. “Did you use a fire direction center?”
“No. We didn’t shoot map grids and we didn’t answer calls for fire, so there was no math.
“For any given range, the firing tables gave us all we needed—charge and elevation. Most times, we didn’t have a radio, just the section lead yelling corrections.
“I should have explained. In the mountains of Korea, we could see for miles. When we saw the enemy in the open, we’d shoot direct lay—each gunner just siting the target directly, estimating the range, and cranking the elevation.
“When we had a good defilade position behind a rise or a finger, we’d shoot direct alignment. We’d lay the tubes on an aiming post, and an observer—a sergeant or lieutenant lying up on the rise—would call down adjustments to bracket the target. It was fast, accurate, and responsive.”
“So you never shot map grids?”
“Never. The 81s did, but we didn’t have an FO. First, we were co-located with the company CP, so no one was confused on our location. Second, we could usually see the target, so there was no confusion there. We used maps to estimate ranges and find dead space, but our effective range was like 1000 meters, 2000 max. If you can see everything for two kilometers, what unseen grids are you going to shoot?”
“Did you fire on the move?”
“Yes. For movement to contact, we’d set up on a rise and overwatch the lead platoon. But that was slow. Sometimes, we just moved as a company, keeping the bipods attached for quick setup.”
The operations officer, Major Western, raised his hand. As a lieutenant, he had commanded an 81s platoon. “Did you do any fires planning?”
“I didn’t. Not with artillery or air. For our company night defense, we’d keep it simple. Three targets, three sets of data. We’d lay the tubes on one target and then rehearse the shifts. Again, no map grids and no lists of targets. No paper at all!” Corcoran smiled.
“Did you ever operate as separate squads?”
“Never. The section is the weapon. Three tubes, one target, twelve rounds.” Corcoran splayed his fingers like an explosion. “Boom!”
“A single tube is a peashooter. Our section was never split for platoons, or patrols, or anything. We always worked for the company CO.”
“You didn’t have a weapons platoon?”
“No. Our lieutenant was the section lead, part of company headquarters. Weapons companies and weapons platoons are administrative units, put together for training. In combat, we break up these units and attach each weapon straight to the leader who needs support.”
“How survivable is the mortar section?”
“As survivable as the rest of the company. The mortar section provides security for the CP. That increases survivability. If the enemy finds you—even behind good dirt—you’ve got to move. We never separated from the company commander.”
Gunner Hill, the battalion weapons expert, spoke up. “You didn’t mention fire support coordination measures.”
Corcoran nodded. “We didn’t shoot at civilians in the village. We didn’t shoot at Baker Company on our left flank. But we rarely drew these lines on our map. It’s just not that complicated—it’s three tubes. You’ve got to be able to set up quickly. You’ve got to be able to estimate range, and you’ve got to hit what you’re aiming at, without mistakes. You’re adding firepower to the company fight. That’s it.”
“What about overhead fire?”
“What about it?”
“We teach these leaders,” the Gunner gestured to the room, “geometries of fire. Range regulations prohibit overhead fire to protect our Marines. In your hill fight, the perimeter was 360 degrees. You fired all night long. How did you move the section to avoid overhead fire?”
Corcoran smiled. “Let’s separate combat from training, Gunner. I don’t know the range regulations, but firing over their heads is the best way to protect your
Marines. Overhead fire is your mission. Overhead fire is why the mortar was invented.”
Brendan McBreen is a retired Infantry Officer. He can be reached at bbmcbreen@gmail.com. Visit his website at https://2ndbn5thmar.com/
Reminds me of Jim Burton's comments in "The Pentagon Wars" about what gets kills in air combat. For all the fancy grids and radars and systems, some 80% of kills were made with "The Mark I Eyeball" system.
Burton advocated cheaper planes, the better to have more of them. Well, Jim's passed into retirement and then the grave, while they built the F-35 instead of his ideas.
Thanks for the interesting article. I really enjoyed the first hand experiences that it shared and the useful insight into mortar tactics.