USNS Mercy ( T - AH - 19 ) The third USNS " Mercy " ( T - AH - 19 ) is the lead ship of her class of hospital ship s in the United States Navy . Her sister ship is the USNS " Comfort " ( T - AH - 20 ) . She was named for the virtue of compassion . In accordance with the Geneva Conventions , USNS " Mercy " and her crew do not carry any offensive weapons , though defensive weapons are available . Firing on the " Mercy " would be considered a war crime . " Mercy " was built as an oil tanker , SS " Worth " , by National Steel and Shipbuilding Company , San Diego , in 1976 . Starting in July 1984 , she was renamed and converted to a hospital ship by the same company . Launched on 20 July 1985 , USNS " Mercy " was commissioned on 8 November 1986 . She has a raised forecastle , a transom stern , a bulbous bow , an extended deckhouse with a forward bridge , and a helicopter - landing deck with a flight control facility . The Mercy class hospital ships are the second largest ships in the U . S . Navy Fleet by length , surpassed only by the nuclear - powered " Nimitz " - class supercarrier s . Her primary mission is to provide rapid , flexible , and mobile acute medical and surgical services to support Marine Corps Air / Ground Task Forces deployed ashore , Army and Air Force units deployed ashore , and naval amphibious task forces and battle forces afloat . Secondarily , she provides mobile surgical hospital service for use by appropriate US Government agencies in disaster or humanitarian relief or limited humanitarian care incident to these missions or peacetime military operations . USNS " Mercy " , homeported in San Diego , is normally in reduced operating status . Her crew remains a part of the staff of Naval Medical Center San Diego until ordered to sea , at which time they have five days to fully activate the ship to an Echelon III Medical Treatment Facility . Like most " USNS " Ships , Mariners from the US Navy ' s Military Sealift Command are responsible for navigation , propulsion , and most deck duties on board . However , the " Medical Treatment Facility " , or hospital on the ship , is commanded by a Captain of the Navy Medical Corps or Navy Nurse Corps . Deployments . Philippine Training Mission . On 27 February 1987 , " Mercy " began training while en route on a humanitarian cruise to the Philippines and the South Pacific . The staff included U . S . Navy , U . S . Army , and U . S . Air Force active duty and reserve personnel ; United States Public Health Service ; medical providers from the Armed Forces of the Philippines ; and MSC civilian mariners . Over 62 , 000 outpatients and almost 1 , 000 inpatients were treated at seven Philippine and South Pacific ports . " Mercy " returned to Oakland , California , on 13 July 1987 . Operation Desert Shield / Desert Storm . On 9 August 1990 , " Mercy " was activated in support of Operation Desert Shield . Departing on 15 August , she arrived in the Persian Gulf on 15 September . For the next six months , " Mercy " provided support to the multinational allied forces . She admitted 690 patients and performed almost 300 surgeries . After treating the 21 American and two Italian repatriated prisoners of war , she departed for home on 16 March 1991 , arriving in Oakland , California , on 23 April . Operation Unified Assistance . USNS " Mercy " departed San Diego on 5 January 2005 en route to the tsunami - devastated regions of South East Asia , where she provided medical care to the victims of the disaster as part of Operation Unified Assistance , and further care as part of Theater Security Cooperation Program 2005 . Combined , she provided 108 , 000 patient services , rendered by members of the Department of Defense , Project Hope , and the United States Public Health Service . Pacific Partnership 2006 . USNS " Mercy " departed San Diego in 2006 as the inaugural deployment of Pacific Partnership , an ongoing Civic Assistance mission designed to " Prepare in Calm to Respond in Crisis " . She visited several ports in the South Pacific Ocean including the Philippines , Indonesia and Banda Aceh . The ship ' s primary mission was to provide humanitarian assistance to these countries , and its staff included several Non - governmental organizations , doctors from the armed services of several countries , as well as active - duty and reserve military providers from many branches of the US armed forces . Pacific Partnership 2008 . USNS " Mercy " , departed San Diego on 14 April 2008 for " Pacific Partnership 2008 " , a 4 - month humanitarian and civic deployment in Southeast Asia and Oceania . " Mercy " , with her 900 officers and sailors , included 300 US health and construction experts . Partners participating in the mission include the nations Australia , Canada , Chile , Japan , the Republic of Korea , New Zealand and Portugal , as well as several non - governmental organizations . Originally intended to visit the Philippines , Vietnam , the Federated States of Micronesia , East Timor and Papua New Guinea , USNS " Mercy " was to be redirected to the Bay of Bengal to provide immediate assistance to victims of the cyclone in Burma , but relief efforts in Burma were called off . On 10 June , the humanitarian mission was temporarily suspended after one of its helicopters was shot at in the strife - torn southern Philippines area of Mindanao . Over the course of the deployment , " Mercy " would treat 91 , 000 patients , including performing 1 , 369 surgeries . Pacific Partnership 2010 . On 24 February 2010 , the Commander of the US Pacific Fleet announced that " Mercy " will be the lead vessel of Pacific Partnership 2010 , a continuation of the recurring humanitarian mission to Southeast Asia and Oceania . For Pacific Partnership 2010 " Mercy " visited Vietnam , Cambodia , Indonesia , and Timor Leste ; treated 109 , 754 patients and performed 1 , 580 surgeries . Pacific Partnership 2012 . May 3 , 2012 saw " Mercy " depart San Diego once again for Pacific Partnership 2012 , the latest deployment of the Pacific Partnership series . In an effort to further expand the scope of the mission of " Preparing in Calm to Respond in Crisis " , many more man hours of Subject Matter Expert Exchange ( SMEE ) with host nations , Veterinary Care , and construction projects were performed compared to past " Mercy " deployments , building the capacity of host nations to respond to regional disasters in a coordinated manner . The ship visited Indonesia , Philippines , Vietnam , and Cambodia carrying personnel not only from the Department of Defense , but also 13 partner nations and 28 Non - Governmental Organizations .