The Battle of Hồng Ngự took place from March to 4 May 1973 when North Vietnamese forces attacked the border town of Hồng Ngự in Dong Thap Province in order to interdict supply convoys into Cambodia. The attack was defeated by South Vietnamese forces assisted by United States bombing of North Vietnamese base areas in Cambodia. Background Since the Khmer Rouge had closed off access to Cambodia's sea ports, supplies for the Khmer Republic were dependent on convoys up the Mekong River from South Vietnam. South Vietnam's border provinces of Kien Phong, Châu Đốc and Kiên Giang, as well as the southern areas of the adjacent Cambodian provinces of Prey Veng, Kandal, Takéo and Kampot, had long been used by the People's Army of Vietnam (PAVN) and Viet Cong (VC) for base areas and lines of communication. In early 1973 the PAVN had up to 11 regiments in Cambodia, all used in South Vietnam except for 3 or 4 deployed against the Khmer National Armed Forces (FANK). The US and South Vietnamese were determined to keep the convoys moving and the Khmer Republic alive, while the PAVN was determined to stop them. The South Vietnamese also sought to prevent PAVN main force incursions and infiltration of supplies and men into South Vietnam and the PAVN sought to keep its lines of communication open through Cambodia and into South Vietnam. The river town of Hồng Ngự, where the Hồng Ngự tributary flows into the Mekong River, became the focal point of the PAVN's attacks to clear impediments to infiltration and interdict the Mekong convoys as they moored at the Republic of Vietnam Navy base at Tân Châu opposite Hồng Ngự before crossing into Cambodia. Battle In March the PAVN concentrated the 174th and 207th Regiments, 6th Division, the 272nd Regiment (detached from the 9th Division) and elements of the 75th Artillery Group in Base Area 704 in Prey Veng Province, Cambodia northwest of Hồng Ngự. With the 207th leading, supported by artillery, the PAVN attacked from Base Area 704 towards Hồng Ngự. Not only did they meet immediate heavy resistance, but their rear area was pounded by USAF B-52's and tactical bombers. While US forces had disengaged from Vietnam on 28 January 1973 in accordance with the terms of the Paris Peace Accords, US military operations in Cambodia and Laos would continue until 15 August 1973 and the USAF was heavily