The Mariel Boatlift officially began April 15, 1980 and ended October 31, 1980, with the arrival of over 125,000 Cubans to Southern Florida from Port of Mariel, Cuba.
As the scale of the boatlift grew, the Coast Guard asked for help. In May 1980 the U.S. Navy dispatched the USS Saipan (LHA-2) and the USS Boulder (LST-1190) to support the Coast Guard by assisting, but not directly transporting, refugees en route to the U.S. Saipan and Boulder temporarily took on board hundreds of refugees in need of humanitarian assistance, medical attention, food, and fresh water. They also refueled private watercraft. The ships' officers and crew were awarded the Humanitarian Service Medal for their work.
Elements of the 1st Battalion, 8th Marines and 1st Battalion, 6th Marines, 2nd Marine Division of Camp Lejeune, N.C., supported the Immigration and Naturalization Service by providing security at Trumbo Point and Truman Annex in May 1980. The Marines supplied interpreters and assisted with processing refugees in Key West. They were awarded the Humanitarian Service Medal and a Certificate of Appreciation for exemplary service. F-4 "Phantom" fighter aircraft from VMFA-312 and later VMFA-251 based at MCAS Beaufort, South Carolina, provided air cover, and those Marines also received the Humanitarian Service Medal.
In May 1980, the U.S. Army dispatched the 503rd Military Police Battalion of the XVIII Airborne Corps at Fort Bragg, North Carolina, to relieve the Florida National Guard units who had been mobilized to handle security and operations at the refugee compounds established in the Miami metropolitan area. The 503rd was augmented by Spanish-speaking soldiers of the 96th Civil Affairs and Psychological Warfare elements of the JFK Special Warfare Center at Fort Bragg. The US Army Military Police Corps worked alongside FEMA and the U.S. Bureau of Prisons and other federal agencies to transfer refugees for long-term detention. U.S. Army personnel who participated in this operation were awarded the Humanitarian Service Medal.