Operation Lam Son 719 or 9th Route Southern Laos Campaign (Vietnamese: Chin dch Lam Sn 719 or Chin dch ng 9 Nam Lo) was a limited-objective offensive campaign conducted in the southeastern portion of the Kingdom of Laos. The campaign was carried out by the armed forces of South Vietnam between 8 February and 25 March 1971, during the Vietnam War. The United States provided logistical, aerial and artillery support for the operation, but its ground forces were prohibited by law from entering Laotian territory. The objective of the campaign was the disruption of a possible future offensive by the North Vietnamese Army (NVA), whose logistical system within Laos was known as the Ho Chi Minh Trail (the Truong Son Road to North Vietnam).

By launching a pre-emptive attack against the NVA's long-established logistical system, the American and South Vietnamese high commands hoped to resolve several pressing issues. A quick victory in Laos would bolster the morale and confidence of the Army of the Republic of Vietnam (ARVN), which was already high in the wake of the successful Cambodian Campaign of 1970. It would also serve as proof that South Vietnamese forces could defend their nation in the face of the continuing Vietnamization withdrawal of U.S. ground combat forces from the theater. The operation would be, therefore, a test of that policy and the ARVN's capability to operate effectively by itself.

However, due to NVA and the Liberation Army of South Vietnam's (Viet Cong) intelligence and preparation beforehand, an inability by the political and military leaders of the U.S. and South Vietnam to face military realities and poor execution, Operation Lam Son 719 collapsed when faced by the determined resistance of a skillful foe. The campaign demonstrated continued deficiencies in ARVN military leadership and that the best units of the ARVN could be defeated by the North Vietnamese, destroying the confidence that had been built up over the previous three years.

The Army of the Republic of Vietnam (ARVN; Vietnamese: Lục quân Việt Nam Cộng hòa; French: Armée de la république du Viêt Nam) were the ground forces of the South Vietnamese military from its inception in 1955 to the Fall of Saigon in April 1975. It is estimated to have suffered 1,394,000 casualties (killed and wounded) during the Vietnam War.The ARVN began as a postcolonial army that was trained by and closely affiliated with the United States and had engaged in conflict since its inception. Several changes occurred throughout its lifetime, initially from a 'blocking-force' to a more modern conventional force using helicopter deployment in combat. During the American intervention, the ARVN was reduced to playing a defensive role with an incomplete modernisation, and transformed again following Vietnamization, it was upgeared, expanded, and reconstructed to fulfill the role of the departing American forces. By 1974, it had become much more effective with foremost counterinsurgency expert and Nixon adviser Robert Thompson noting that Regular Forces were very well-trained and second only to the American and Israeli forces in the Free World and with General Creighton Abrams remarking that 70% of units were on par with the US Army. However, the withdrawal of American forces by Vietnamization meant the armed forces could not effectively fulfill all of the aims of the program and had become completely dependent on U.S. equipment since it was meant to fulfill the departing role of the United States.At the ARVN's peak, an estimated 1 in 9 citizens of South Vietnam were enlisted, and it had become the fourth-largest army in the world composed of Regular Forces and the more voluntary Regional and Village-level militias.Unique in serving a dual military-civilian administrative purpose, in direct competition with the Viet Cong, the ARVN had also become a component of political power and suffered from continual issues of political loyalty appointments, corruption in leadership, factional infighting, and occasional open internal conflict.After the fall of Saigon to North Vietnam's People's Army of Vietnam (PAVN), the ARVN was dissolved. While some high-ranking officers had fled the country to the United States or elsewhere, thousands of former ARVN officers were sent to re-education camps by the communist government of the unified Socialist Republic of Vietnam. Five ARVN generals committed suicide to avoid capture by the PAVN/VC.