Army officials from Fort Benning, Georgia, confirmed Moore's death in a statement Saturday evening.
Moore, who the Army described as a "legendary combat leader," died at his home in Auburn, Alabama, according to the statement. He is survived by three sons, two daughters, 11 grandchildren and four great-grandchildren.
Moore was preceded in death by his wife, Julie Compton, in 2004.
His death came after having had a stroke a few days before, according to one of his children, WFSA reports.
The general is best known for his actions during the Battle of Ia Drang, where he served as the commander of 1st Battalion, 7th Cavalry Regiment.
Within 20 minutes of the first shot of that deadly battle, Moore's battalion was vastly outnumbered and assaulted by hundreds of enemy furiously determined to overrun the Americans, according to the Army.
After a three-day bloodbath, the enemy quit the field, leaving more than 600 of their dead on the battlefield.
Moore was awarded the Distinguished Service Cross, the nation's second highest award for valor, for his actions during that battle.
Moore was commissioned as a second lieutenant of infantry after graduating from West Point in 1945, according to the Army. He served with the 187th Glider Infantry Regiment in Sapporo, Japan, then was reassigned to the 82nd Airborne Division at Fort Bragg, North Carolina. There, he volunteered for the Army's Airborne Test Section, where he jump tested experimental parachutes, making more than 130 test jumps in two years.
Moore then was assigned to the 17th Infantry Regiment, 7th Infantry Division, where he commanded a heavy mortar company and an infantry company, according to the Army. He served as a regimental operations officer during the Korean War before serving at Fort Benning and undergoing air assault and mobility training and testing.
Moore and Gibson in 2016
During the Vietnam War, Moore commanded 1st Battalion, 7th Cavalry Regiment. It was the actions of that unit during the Battle of Ia Drang in 1965 that became the basis of his book "We Were Soldiers Once, and Young."
The book became a movie in 2002, with Mel Gibson portraying Moore.
Tensions in Vietnam
America’s military involvement in Vietnam began by sending advisers.
Then, more combat troops.
“We intend to convince the communists that we cannot be defeated by a force of arms,” then President Lyndon B. Johnson told the world while trying to convince an American public frightened of communism that such an evil must be stopped from spreading.
The escalation of the U.S military role in Southeast Asia came in the early 1960s not long after a threat of nuclear war with the Cuban Missile Crisis and less than two decades since World War II and the Korean War.
Much of the nation was skeptical about fighting another so soon, but American soldiers nonetheless trained and prepared in the proud tradition of those who fought before them.
Moore, a colonel at the time, began training elements of the famous 7th Cavalry at nearby Fort Benning, Georgia, in a new concept of warfare that involved helicopters flying deep into enemy territory and finding landing zones to deploy troops.
It would be one such landing zone where a battle soon would erupt and cast striking parallels between Moore and another commander of the 7th Cavalry less than a century earlier – Gen. George Armstrong Custer, infamously known for Custer’s Last Stand before he and his men were all killed.
Fort Benning’s role
The North Vietnamese Army, referred to as NVA, wanted to engage and kill Americans to demonstrate its determination in evicting yet another invader, as it had done years earlier with the French.
However, it knew it would be costly to engage the American military where it was strongest, so it tried to lure the fight into jungle warfare far from central bases. The U.S. Army, on the other hand, issued orders to Moore and his troops to “seek and destroy” the enemy.
A small open field was found near where enemy activity was suspected, and it was designated Landing Zone X-ray, or LZ X-ray for short. However, only a few helicopters at a time could land in the LZ.
Moore was the first to step foot on what quickly would become a bloody battlefield.
“When I took command of that battalion, I stood in front of my troops and made a short speech,” Moore recalled in later interviews, referring to the unit’s training at Fort Benning. “Get rid of second-place trophies, because we’re going to be the best.
“And I promise you, when we go into combat, and I think we shall because the Vietnam War is heating up,” he said, “When we go into combat, I will be the first man on the ground, and the last man out, and I will leave no man behind.”
That day came on Nov. 14, 1965.
The Battle of la Drang Valley
During a 1993 documentary feature filmed by ABC television, Moore was asked if he had any idea what awaited him and his men when they first arrived at LZ X-ray.
“No, none whatsoever,” Moore replied.
What neither Moore nor any of the senior officers who ordered him on the mission knew was: On the mountain overlooking the valley and LZ was a base camp for the NVA – and three enemy battalions.
Moore and his first small group of helicopters had landed right in the enemy’s lap.
Before Moore had accumulated about 150 men and while waiting for more to come, the North Vietnamese immediately attacked with a force of about 1,600 troops, which later would grow into thousands more.
Gunfire and mortar fire began ripping the ground and the men to shreds. The small and vastly outnumbered American force returned fire with devastating effect, slowing the enemy advance.
Moore, however, made an early tactical move that would carry him into military textbook lore and no doubt saved his command.
Instead of following natural instincts and gathering all his force within a tight perimeter to defend itself, as Custer had done in fighting American Indians in his last stand, Moore immediately recognized that he had to protect his landing zone, or there would be no hope of re-enforcements making it to the ground to join the fight.
Thinking about how his enemy might approach the battle, he quickly ordered a portion of his troops to hustle across the field under fire and establish a defense line on the other side of it.
Almost exactly as Moore had predetermined, the enemy attacked the skirmish line, while also pouring troops into the fight against Moore from all sides.
The battle quickly grew and raged into a bloody fight, much of it hand-to-hand combat.
Helicopters flown by brave pilots did what they could to deliver help, but they were easy pickings for the snipers and machine gunners surrounding Moore and his men, who protected the LZ as long as they could.
Eventually, NVA troops broke through the lines and into the clearing. It was a desperate situation for the outmanned Americans who now had enemy soldiers fighting them within the ranks. There were few options left.
Moore sounded the call of “Broken arrow!”
That was the command given when an American unit was overrun, and it meant that all available air power was to respond and attack the position with everything it could drop.
Moore later assumed command of 3rd Brigade, 1st Cavalry Division, and led it through several major campaigns in 1966, earning a Bronze Star Medal with Valor - the third of his career - for carrying wounded soldiers to safety under "withering small and automatic weapons fire," according to the Army.
As a two-star, Moore commanded the 7th Infantry Division in Korea. He was later promoted to lieutenant general in 1974 and assigned to the Pentagon as the deputy chief of staff for personnel.
Moore, a native of Bardstown, Kentucky, retired from the Army in 1977.
The funeral mass will be held at St. Michael's Roman Catholic Church in Auburn, followed by a memorial service and internment at Fort Benning.
Additional details are being finalized and will be announced soon, Fort Benning officials said.
Memorial donations may be made to the Ia Drang Scholarship Fund, which was established in 1994 using proceeds from his book and speaking engagements. The fund is used to help the children and grandchildren of the veterans of the Ia Drang battles.
Please send checks to the Ia Drang Scholarship Fund, c/o Executive Director, 1st Cavalry Division Association, 302 North Main, Copperas Cove, TX 7652