What to Know About Navy Hospital Ships

The USNS Mercy and Comfort Serve as the Navy's Hospital Ships

US Navy Hospital ship

U.S. Navy hospital ships provide afloat, mobile, acute surgical medical facilities when called upon by the military. There have been additional medical vessels serving in other roles (ambulance vessels, rescue ships, and evacuation ships).

How Many Hospital Ships Does the U.S. Have?

The U.S. Navy has two hospital ships: the USNS Mercy (T-AH-19) and the USNS Comfort (T-AH-20). These ships are unmistakable, with their gleaming bright white hulls and huge red crosses painted on the sides.

Both ships are converted San Clemente-class supertankers that were built in the 1970s by the National Steel and Shipbuilding Company, and then purchased by the Navy and converted to hospital ships in the late 1980s. Military Sealift Command operates both ships.

Geneva Convention Status

Hospital ships enjoy a special status, which was internationally recognized under the second Geneva Convention of 1906 and the Hague Convention of 1907 that protects them from attack. The hospital ships must meet specific restrictions outlined in Article Four of the Hague Convention X in order to enjoy this protection:

  • The ship must be clearly marked and lighted as a hospital ship
  • The ship should give medical assistance to wounded personnel of all nationalities
  • The ship must not be used for any military purpose
  • The ship must not interfere with or hamper enemy combatant vessels
  • Belligerents, as designated by the Hague Convention, can search any hospital ship to investigate violations of the above restrictions
  • Belligerents will establish the location of a hospital ship

The convention established that during times of war, hospital ships would be exempted from dues and taxes imposed on vessels in the ports of the states that ratify the treaty.

International Law at Sea

The San Remo Manual on International Law Applicable to Armed Conflicts at Sea, adopted in June 1994, stipulates that a hospital ship violating legal restrictions must be duly warned and given a reasonable time limit to comply. If a hospital ship persists in violating restrictions, a belligerent is legally entitled to capture it or take other means to enforce compliance. A non-complying hospital ship may only be fired on under the following conditions:

  • Diversion or capture is not feasible
  • No other method to exercise control is available
  • The violations are grave enough to allow the ship to be classified as a military objective
  • The damage and casualties will not be disproportionate to the military advantage

In all other circumstances, attacking a hospital ship is a war crime.

U.S. Military Hospital Ship Needs in WWI and WWII

During the first World War (a.k.a., “The Great War”), hospital ships were first used on a massive scale, but later mainly were used to transport sick and wounded military personnel from the theaters of operations to hospital facilities in the United States. 

The U.S. military again used hospital ships World War II, but their use was based on who operated them. The Navy wasn’t the sole branch of the U.S. Armed Forces to operate hospital ships, as for a time the Army also operated them (in fact, the Army operated a fleet of ships of its own—see Ship Hull Classifications – The Rest of the Armed and Uniformed Forces)

During World War II, the Army decided it was their own responsibility to transport their wounded, and so they wanted to arrange evacuation with their own ships. There were a total of 27 hospital ships in operation for the evacuation of Army casualties. The Army Transport Service operated 24 hospital ships which were manned by civilian crews (employees of the Army Transport Service) and Army medical staff

Army and Navy Ships

Meanwhile, the Navy operated three hospital ships (AH-6 USS Comfort, AH-7 USS Hope and AH-8 USS Mercy) that were manned by the Navy but staffed by the Army Medical Department. 

However, as noted, the Navy and Army operated hospital ships with different purposes—Navy hospital ships were fully equipped hospitals designed to receive casualties direct from the battlefield and also supplied to provide logistical support to front line medical teams ashore, while Army hospital ships were essentially hospital transports intended and equipped to evacuate patients from forward area Army hospitals to rear area hospitals (or from those to the United States).

Most of the U.S. military’s hospital ships started out as craft with a different role, and renovated to become hospital ships. The three Navy hospital ships were the only vessels built as hospital ships for the U.S. Army fleet—the 24 U.S. Army-operated hospital ships were converted from other types of ships. By the end of WWII, the Navy had 15 hospital ships in operation.

Some Navy hospital ships were prior Army vessels. For example, when the Spanish-American War broke out in 1896, the passenger ship John Englis was purchased by the Army for use as a hospital ship, and renamed Relief. In 1902, the Navy acquired the ship and operated it as USS Relief until 1918, when she was renamed to Repose to allow the name of Relief to be assigned to AH-1 USS Relief.

Today's Need for Hospital Ships

Though today the United States Navy operates only two dedicated hospital ships, hospital and medical ships of many types have been part of the Navy at least since 1801. Both the Comfort and the Mercy play a role in Military Sealift Command (MSC). The ships are operated, navigated, and maintained by a civil service mariner staff, or CIVMAR. These are federal government employees who pursues a civil service Navy career. The Navy command is responsible for the hospital and its staff.

The USNS Comfort and Mercy normally sit pier-side with a reduced number of crew personnel. Typically there will be 18 CIVMARs and around 50 Navy hospital crew aboard to maintain the ship in a “ready status." When called into action, the ships will add more than 60 CIVMARs and over a thousand military medical staff and render aid wherever needed. They are often asked to spring into action when there is a global humanitarian crisis, such as a direct hit by a typhoon or an earthquake.

The USNS Mercy is based out of San Diego, Calif. The USNS Comfort is based out of Norfolk, Va.