River Division 531 (RIVDIV 531)

River Division 531 (RIVDIV 531) was a unit of the United States Navy’s Mobile Riverine Force (Task Force 117) during the Vietnam War. Activated in the late 1960s, RIVDIV 531 operated heavily armored river patrol boats (PBRs and later ASPBs) in the Mekong Delta to interdict Viet Cong supply lines and support ground operations. The division participated in numerous combat patrols, convoy escorts, and search-and-destroy missions in the complex network of rivers and canals. Its actions were instrumental in the U.S. effort to control critical waterways and disrupt enemy movements throughout the region.