He joined the Army in 1969 and was commissioned as a lieutenant.[2] His first assignment was as a platoon leader in the 2nd Battalion, 30th Infantry Regiment, 3rd Infantry Division based in West Germany. There he encountered the declining morale of the Army with six members of his platoon in prison for violent crimes and rampant drug abuse.[1]: 490
He volunteered for service in South Vietnam as an adviser and attended adviser and Vietnamese language training.[1]: 490 Promoted to captain, he arrived in South Vietnam in December 1971.[1]: 489 His first assignment was with the Royal Thai Army Expeditionary Division until it was withdrawn in February 1972 and he was then assigned to the Army of the Republic of Vietnam (ARVN) 48th Regiment, 18th Division based at Xuân Lộc.[1]: 490 He described his role as a "phone booth on the ground", "able to tap into the U.S. air support remaining in country – helicopters, tactical helicopters, tactical air, medevacs".[1]: 490 On his third patrol his unit was ambushed in a rubber plantation and he was wounded by shrapnel, the battalion command unit fled the area and he and several other survivors took 12 hours to escape from the ambush, eventually being picked up by vehicles near an ARVN outpost.[1]: 490–1
During the Easter Offensive two battalions from the 18th Division, organised as Task Force 52, which had unsuccessfully attempted to reinforce other ARVN units in the Battle of Loc Ninh, withdrew to An Lộc. On 12 April Willbanks and another adviser volunteered to replace U.S. advisers who had been wounded and they were dropped by helicopter into An Lộc. The Battle of An Lộc began the following morning with an assault by People’s Army of Vietnam (PAVN) tanks.[1]: 495 Willbanks stayed in An Lộc throughout the siege calling in the air support and resupply that was crucial to the defeat of the PAVN. On 9 July as the siege was nearing its end, he was among the advisers who went to meet with Third [Military] Regional Assistance Command deputy commander Brigadier GeneralRichard J. Tallman and was wounded by the PAVN artillery fire that mortally wounded Tallman.[1]: 496–8
He earned a master’s in management from Texas A&M in 1979.[2]
He became a civilian instructor at the CGSC in 1992. He received his master’s in history from the University of Kansas in 1992 and then his doctorate in history there in 1998. He eventually became director of the Department of Military History and General of the Army George C. Marshall Chair of Military History at CGSC before retiring in May 2018 and being made the eighth CGSC Professor Emeritus.[2]
He has written numerous military history books, primarily focussed on the Vietnam War. He was a consultant and interviewee for The Vietnam War (TV series).[3]
