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.
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.
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 76522.