The Battle of Hue
A gross lack of operational intelligence on enemy planning for the Tet Offensive resulted in the achievement of nearly total surprise by Communist forces. U.S. intelligence had correctly identified large buildups along the Vietnamese Demilitarized Zone (DMZ) and the Laotian border, but had failed to accurately forecast the objective of these preparations.
American intelligence knew that People's Army of Vietnam (PAVN) regiments were within a day's march from Hue and were preparing for an attack — somewhere — yet completely failed to identify the intent and magnitude of the assault. There were no reliable human intelligence resources in Hue to identify the several hundred Viet Cong (VC) guerrillas who had infiltrated the city a couple of days prior to the attack in order to facilitate the PAVN invasion.
Located approximately 80 kilometers southeast of the DMZ, Hue was the predominant cultural, spiritual, and educational center of Vietnam. The city comprises two distinct towns separated by the Perfume River, which flows from west to east. On the northern bank sits the Citadel, which once served as the residence for Annamese emperors, while the southern bank primarily consisted of residential areas, along with the University of Hue and the French provincial capital.
The Surprise Attack
At 03:40 on January 31, 1968, the North Vietnamese army and their Viet Cong allies launched their attack and by shortly after 8:00 the Viet Cong flag was flying over the Citadel. Within a few hours, Communist forces had seized control over the entire city save for two key objectives: The headquarters of the lst Infantry Division of the Army of the Republic of Vietnam (ARVN), located within the Citadel, and a U.S. compound for Military Assistance Command, Vietnam (MACV) advisers, situated on the south side of the Perfume River.
On the fourth day of the fighting, the United States III Marine Amphibious Force managed to establish a command post in the MACV compound. Two Marine Corps companies were directed to begin the painstaking process of clearing the south side of Hue building by building, through the prepared defenses of a determined enemy. With every street a prepared kill zone monitored by snipers, the Marines were forced to adopt novel tactics to attain their objectives, learning through a costly process of trial and error. Skilled in the conduct of rural and jungle warfare against hit-and-run ambushes, Marines in Hue now faced urban defense in depth. Tanks were the sole advantage in weaponry permitted by U.S. rules of engagement and their ability to maneuver was greatly restricted by PAVN B-40s, a variant of the Russian RPG-2 hand-held antitank grenade launcher produced by North Vietnam. U.S. rules of engagement prohibited aerial bombardment and naval surface fire. In order to advance, small infantry teams armed with recoilless rifles and accompanied by tanks opened routes through walls and buildings, while self-propelled antiaircraft weapons and mortars provided suppressive fire. While enabling troops to advance, these tactics did not prevent high American casualty rates.
By the fifth day of fighting, Marine companies had acquired a number of tear gas launchers. This non-lethal weapon helped them to force North Vietnamese and Viet Cong soldiers out of buildings. The enemy could now be engaged in the open, while U.S. troops avoided the need to fire into buildings indiscriminately, risking civilian lives. On February 10 the south side of the city was declared secure. In the days that followed, Marines swept the southern portion of the city of all Communist forces. During these sweeps, Marines began to uncover mass graves of Hue residents executed during its occupation.
Once Hue had been captured, Viet Cong provisional authorities replaced the existing municipal government with a "revolutionary administration". Working from lists previously developed by intelligence officers, the Viet Cong began to round up South Vietnamese soldiers, civil servants, political party members, Vietnamese and American civilians as well as other foreigners. Names on the lists were called out over loudspeakers, with orders to report to a local school. Since the Communists took great care to bury and conceal the dead, it took nearly a full year for U.S. forces to grasp the true scale of the genocide. The South Vietnamese were to eventually recover 3,000 bodies from mass graves around the city, with an additional 2,000 people remaining unaccounted for. Furthermore: In Hue 1968: A Turning Point of the American War in Vietnam, Mark Bowden estimates that between one and two thousand people were killed in Hue by South Vietnamese forces after the city was retaken.
Heavy combat in the Citadel continued through February 20 when PAVN began a phased withdrawal, returning to their bases in the hills to the southwest of the city. Efforts to clear the Citadel were led by Vietnamese Marines and ARVN troops, as well as U.S. Marines.
A Question of Supplies
Confined to an urban environment, both sides attempted to cut supplies off from their opponents, with varying degrees of success. On the second day of the battle, a battalion from the U.S. 1st Cavalry Division was deployed to a landing zone along Highway 1, approximately 10 kilometers northwest of Hue, in an effort to sever North Vietnamese Army lines of communication. Through several days of fighting they were unable to isolate the city. Thus, Communist forces continued to receive reinforcements and fresh supplies from the Vietnamese interior.
Communist forces repeatedly attempted to demolish the An Cuu Bridge, but failed until five days into the fighting. Highway 1 stretched 13 kilometers northwest from the U.S. Army and U.S. Marine Corps combat base at Phu Bai to the An Cuu Bridge, crossing the Phu Cam canal and continuing north to the outskirts of Hue. The bridge was therefore vital to efforts to resupply and reinforce units attempting to retake Hue. By the time that the bridge was dropped, five U.S. Marine infantry companies and additional ARVN forces had arrived to reinforce the MACV compound on the southern bank of the Perfume River. American forces also gained control of the Navy Landing Craft Utility ramp and helicopter landing zone near the MACV headquarters.
Communist forces eventually succeeded in dropping two key bridges to sever Highway 1, thereby isolating the city by ground, but by failing to destroy the An Cuu Bridge they failed to completely isolate the city. Controlling the landing zone and boat ramp immediately adjacent to the MACV compound allowed U.S. Marines to effectively use the Perfume River as an alternate line of supply and communications, sourced from naval vessels in the South China Sea. North Vietnamese inability to sever American air, land, and sea lines of communication likely cost them the battle.