Vung Tau, the fifth largest city in South Vietnam, with nearly 40,000 people, was also the southernmost, major port facility in the country. Located in Phuc Tuy Province in III Corps, Vung Tau was more than 400 miles south of Hue. It was formerly known as Saint Jacques. The port at Vung Tau was the main support center for the southern area of South Vietnam, and was situated at the entrance to the Mekong River system leading into Saigon. Vung Tau was also the support area for the Mobile Riverine Force.