Gregory Peck, left, and Ronnie Knox, right, during filming of “Pork Chop Hill.” Looking on in center is Joseph Clemons Jr., whose experiences in Korea are being retold in the movie. (Bettmann/Bettmann Archive)

On the official records it was Hill 255. The mountainous Korean outpost, nicknamed Pork Chop Hill for its vague resemblance to the loin cut, had been the site of frequent skirmishes since the conflict began in 1950. The land itself, like many of the hills just beyond the Allies’ main line of resistance, had no inherent tactical value.

But in spring 1953, it became one of the bloodiest and most controversial combat operations of the Korean War and a defining moment in the life of Joseph G. Clemons Jr., a 25-year-old first lieutenant and U.S. Military Academy at West Point graduate who commanded King company in the 7th Infantry Division.

His actions, defending the crest of the hill with a small, beleaguered unit, would result in his immortalization in a best-selling book by eminent military historian S.L.A. Marshall and a Hollywood film in which he was portrayed by Gregory Peck. He died May 15 at 90, after a long and highly decorated military career in which he rose to the rank of colonel.

A Baltimore high school graduate, Col. Clemons had enlisted in the Army at 17 to qualify for the G.I. Bill. He later won an appointment to the U.S. Military Academy at West Point, N.Y., and obtained his degree in 1951. The next year, within days of his arrival in Korea, his defense of a position near Kumhwa that involved unrelenting bunker-to-bunker combat earned him the Distinguished Service Cross, the military’s second-highest award for valor.

But it was his actions at Pork Chop Hill over two days in April 1953 that became the centerpiece of his military legacy. Stalemated truce talks and prisoner-of-war exchanges about 60 miles away at Panmunjom imbued the otherwise militarily worthless hill with immense political and propaganda value.

The Chinese, which formed the main ground forces of the Communist North and occupied most of the front-line area, staged a major attack on April 16, followed by an Allied counterattack the next day. Whichever side prevailed would emerge at the negotiating table with an advantage that could be parlayed into a bargaining chip for important concessions.

As part of the effort to repulse the Chinese, Col. Clemons was tasked before dawn on the 17th with advancing up the rear slope of the steep terrain with 135 soldiers, clearing out the enemy bunkers and trenches, and maintaining control until relief arrived; two platoons from another company were to proceed from other directions.

“Hit the hill hard and get to the top as fast as the men can go,” Col. Clemons told the leaders of his unit. “Success depends on speed. We must close before daylight.”

It proved a grueling, time-consuming task, with men weighed down by loads of ammunition and others carting boxes of grenades over rocky land strewn with wire. As they scaled the hill, a free-for-all of grenade and artillery fire caused mass casualties on both sides. At daybreak, only 25 members of his company remained unwounded. They were dug in high on the hill, a virtual moonscape of artillery-blasted craters and collapsed bunkers.

He could not push forward any further and still ensure safe evacuation of the wounded. His supply lines were stressed. Requests for water, plasma, flamethrowers, ammunition and working radios largely went unfulfilled. His soldiers were physically depleted as they sheltered in a bunker. The Chinese still held an estimated two-thirds of the trench line, and the fighting flared up at intervals.

“He did not have enough able-bodied men to take the hill by storm; he had too many to plead fatal weakness,” Marshall wrote. “The few who remained fighting were dangerously dispersed; to withdraw and regroup them would yield hard-won ground to the enemy snipers.”

Col. Clemons radioed division headquarters for support. A fresh unit arrived — including, much to his surprise, his brother-in-law — under the impression that the operation was almost over, just a mop-up job.

In one near-farcical moment, an Army public information officer and two photographers also managed to get through. Their instructions to chronicle a glorious victory were met with weary incredulity by Col. Clemons and his skeleton crew. “Forget the pictures,” he reportedly told the PIO. “I want you to carry a message to Battalion.” He scribbled a note: “We must have help or we can’t hold the hill.”

According to Marshall’s book, Col. Clemons’s dire radio and written messages had never explicitly stated the high casualty rates, and his commanders had assumed that the men were fatigued but could nonetheless fulfill their mission.

It was only after others also sent in their reports that relief began to pour in after the Japan-based Far East Command decided the hill was worth retaining at all costs. Reinforcements finally arrived late on the 17th, and Col. Clemons returned to base. Only 14 of his men walked down the hill, with 121 killed or wounded over the previous day.

“Rarely in combat history has a force of the size committed on Pork Chop taken such losses . . . and nevertheless continued to hold their position,” Col. Clemons’s Silver Star commendation stated.

By dawn on the 18th, American forces prevailed after a barrage directed against the remaining Chinese. During the battle, 243 Americans were killed in action on Pork Chop Hill and an estimated 1,500 Chinese died, with many more wounded on both sides.

The U.S. victory was short-lived. The Chinese returned that July en masse and gained the upper hand after Gen. Maxwell Taylor, commander of the U.S. Eighth Army and United Nations forces in Seoul, decided to abandon the hill at that point.

In his book “The Coldest Winter,” author David Halberstam described Pork Chop Hill as “almost a symbol of the emptiness of the last stages of the war, so much to be invested for so little gain.”

Joseph Gordon Clemons Jr. was born in Cleveland on April 30, 1928, and grew up in Plant City, Fla., and Baltimore, where his father was a railroad freight conductor.

After serving in Korea, Col. Clemons held infantry commands and underwent Ranger training (he was later inducted into the Ranger Hall of Fame). During the Vietnam War, he received the Bronze Star Medal for helping direct by helicopter the medical resupply and evacuation of a unit pinned down by withering enemy attack.

H. Norman Schwarzkopf, the future general and Persian Gulf War commander, served under him in Vietnam and called him “a straight-forward, no-nonsense soldier and one of the best bosses I’ve ever had.” In his memoir, he recounted how Col. Clemons’s lack of political tact with superiors — a refusal to bow to decisions he felt would endanger his men — caused his career to stall and hindered his promotion to general.

After his military retirement in 1977, Col. Clemons spent many years in Hawaii until settling in Hendersonville, N.C., where he was a senior warden of his Episcopal church and was involved with a Meals on Wheels program. He died at his home in Hendersonville of complications from pneumonia, said a granddaughter, Makana Clemons.

In 1952, he married Cecil Russell, the sister of a West Point classmate. In addition to his wife, of Hendersonville, survivors include three children, Michael J. Clemons of Macon, Ga., Susannah Shultis of Hendersonville and Joseph G. Clemons III of Luxembourg; 10 grandchildren; and three great-grandchildren.

William Russell, a Korean War veteran and author of “Stalemate & Standoff, the Bloody Outpost War” (1993), said the actions at Pork Chop Hill went “virtually unreported because all the U.N. correspondents were at Panmunjom” covering the armistice talks. Marshall’s 1956 book “Pork Chop Hill” brought the battle to wider attention and was the basis for the movie three years later.

Col. Clemons went to Hollywood as a technical adviser and said he was determined to make the film — one of the grittier mainstream war dramas of the era — as realistic as possible, or at least avoid some of the most wincing mistakes of previous combat movies.

“It’s pretty laughable when a single hand grenade blows up a whole house,” he remarked at the time. “Or when you see a machine-gun blast that either mows down everyone in sight or spares them all.”