For the first time in decades, two U.S. Navy command ships are in action at the same time. One (USS Mount Whitney) is supporting the air and naval operations in Libya, while the other one (USS Blue Ridge) is assisting relief operations off Japan. The U.S. only has two of these ships, as two older ones were retired in 2005 and 2006, and orders for new ones have been cancelled.
Command ships give the United States Navy the ability to position a major headquarters, complete with powerful communications and computer capability, as well as working and living accommodations for hundreds of personnel. During World War II, command ships were found to be invaluable for running large amphibious operations, and giving the ground commanders a place to work before they moved their headquarters ashore. Command ships were also invaluable for providing mobile headquarters for the huge American Pacific fleet that, during World War II, was constantly moving long distances, and had to coordinate the repositioning of huge quantities of supplies, and thousands of ships and aircraft. With no more large amphibious operations to handle, command ships evolved into their present form, as mobile headquarters ready to go anywhere they were needed.
Despite the availability of satellite communications today, the command ship is still valuable, and an insurance policy in case some of your satellites get shot down. Earlier command ships were converted amphibious or transport ships. The Blue Ridge and Mount Whitney, however, were built as command ships in the late 1960s. These are 18,900 ton vessels with a top speed of 42 kilometers per hour and has a crew of 325. There are accommodations for several hundred command personnel. Armament is light, consisting of two Phalanx anti-missile cannon, two 25mm autocannon and four 12.7mm machine guns. There are also missile and torpedo decoy systems. There is also a helicopter pad, and one SH-60 helicopter is carried.
The major equipment on board are computerized communications systems that can handle lots of encrypted (coded) message traffic with lots of different allies. One of these ships is based in Italy, the other in Japan. When not at sea, they serve as floating headquarters, usually for one of the navy's fleets, while tied up at pier side.