William was born in Dehart, Kentucky on the 30th of November, 1919. He attended and graduated from Morgan County High School before going to Morehead State Teachers College. After two years, William enlisted in the US Marine Corps and completed his recruit training at Marine Corps Recruit Depot Parris Island and then continued on to parachute training at the Naval Air Station in Lakehurst, New Jersey. Once becoming a paramarine, he became an instructor at the Parachute Training School in New River, North Carolina, before entering Officer Candidate School in May of 1943.

Three months later, William was commissioned as a Second Lieutenant and was assigned to Company E, 2nd Battalion, 26th Marine Regiment, 5th Marine Division at the Marine Corps Base Camp Pendleton, California. He was a platoon leader when they deployed to the South Pacific during World War 2 and William was wounded twice during the Battle of Iwo Jima. Once healed, he returned to his unit and took the place of the Company Commander during the last two weeks of the campaign. He was then promoted to First Lieutenant and placed in command of his company. His actions during Iwo Jima earned him a Silver Star and two Purple Hearts and when he returned to the States, he was stationed in Milwaukee, Wisconsin and Camp Lejeune, North Carolina, before ending up in Altoona and Philadelphia, Pennsylvania.

By the time William deployed to Korea, he was a Captain and company commander of Company F and it was his actions during the Battle of Chosin Reservoir that would earn him another Purple Heart and the Medal of Honor. The citation reads:

For conspicuous gallantry and intrepidity at the risk of his life above and beyond the call of duty as Commanding Officer of Company F, Second Battalion, Seventh Marines, First Marine Division (Reinforced), in action against enemy aggressor forces in Korea from November 28, to December 2, 1950. Assigned to defend a three-mile mountain pass along the division's main supply line and commanding the only route of approach in the march from Yudam-Ni to Hagaru-ri, Captain Barber took position with his battle weary troops and, before nightfall, had dug in and set up a defense along the frozen snow-covered hillside. When a force of estimated regimental strength savagely attacked during the night, inflicting heavy casualties and finally surrounding his position following a bitterly fought seven-hour conflict, Captain Barber, after repulsing the enemy, gave assurance that he could hold if supplied by air drops and requested permission to stand fast when orders were received by radio to fight his way back to a relieving force after two reinforcing units had been driven back under fierce resistance in their attempts to reach the isolated troops. Aware that leaving the position would sever contact with the 8,000 Marines trapped at Yudam-ni and jeopardize their chances of joining the 3,000 more awaiting their arrival in Hagaru-ri for the continued drive to the sea, he chose to risk loss of his command rather than sacrifice more men if the enemy seized control and forced a renewed battle to regain the position, or abandon his many wounded who were unable to walk. Although severely wounded in the leg the early morning of the 29th, Captain Barber continued to maintain personal control, often moving up and down the lines on a stretcher to direct the defense and consistently encouraging and inspiring his men to supreme efforts despite the staggering opposition. Waging desperate battle throughout five days and six nights of repeated onslaughts launched by the fanatical aggressors, he and his heroic command accounted for approximately 1,000 enemy dead in this epic stand in bitter sub-zero weather, and when the company was relieved, only 82 of his original 220 men were able to walk away from the position so valiantly defended against insuperable odds. His profound faith and courage, great personal valor and unwavering fortitude were decisive factors in the successful withdrawal of the division from the deathtrap in the Chosin Reservoir sector and reflect the highest credit upon Captain Barber, his intrepid officers and men and the United States Naval Service.

Once recovered from his wounds, William was assigned to the Marine Corps Recruit Depot in San Diego as a company commander in April of 1951. He then became the executive officer of the 1st Recruit Training Battalion and was promoted to Major in July of 1952. The following month, on the 20th of August, William received the Medal of Honor from President Truman in a ceremony at the White House.

After the Korean War, William went to Fort Benning, Georgia to complete the Advanced Infantry Course and then went on to serve as the operations and training officer at Camp Lejeune. Over the next nine years, William would serve in Thailand, Quantico, Okinawa, and back to Camp Lejeune was promoted to Lieutenant Colonel and Colonel. He was transferred to the 2nd Marines, 2nd Marine Division, as the division plans officer, assistant chief of staff, intelligence, and finally as commanding officer of the 2nd Marines. William was ordered to Vietnam as a Psychological Operations Officer with the III Marine Amphibious Force, Military Assistance Command. His actions during his last tour of active duty earned him the Legion of Merit with a combat V device. The following year, on the 1st of May, 1970, William retired from the Marine Corps after thirty years of service and combat deployments in three wars. He became a military analyst for the Northrop Corporation and he and his wife of 59 years had three children. William Earl Barber died in his home of bone marrow cancer on the 19th of April, 2002 at the age of 82. His wife, Ione, died four years later and her ashes were interred with William in Arlington Nation Cemetery: Section 66, Grave 6904.