Includes over 30 maps and illustrations For several years, the eastern part of the Laotian panhandle was used by North Vietnam as a corridor for the infiltration of personnel and materiels required to sustain its war efforts in South Vietnam and Cambodia. In addition to the Ho Chi Minh Trail, the eastern panhandle contained many logistic installations and base areas. After the 18 March 1970 change of government in Cambodia which closed the port of Sihanoukville to the enemy, this trail-base area complex in lower Laos became even more important to North Vietnam in its prosecution of the war in the South. The real hub of this entire complex, where transportation and storage activities were coordinated, was Base Area 604 located west of the Demilitarized Zone and surrounding the district town of Tchepone. To disrupt the flow of enemy personnel and supplies into South Vietnam, a ground attack was launched across the Laotian border against this enemy hub of activity on 8 February 1971. Operation LAM SON 719 was conducted by I Corps with substantial U.S. support in firepower and heli-lift but without the participation of U.S. advisers with those ARVN units fighting in Laos. As a test of Vietnamization, this operation was to demonstrate also the progress achieved in combat effectiveness by the Republic of Vietnam Armed Forces. Further, LAM SON 719 achieved the objective of forestalling a Communist offensive in the spring of 1971.