Submarine warfare has been around a while. Primitive subs were used with mixed results from the Revolutionary War up until World War I, when advances were made in propulsion and torpedoes.
However, it was the Germans who most effectively used their submarines, called U-boats, against allied shipping during World War I. The allies took note and began to modernize their submarines. By the time the United States became involved in World War II, the advances were pivotal to the success of the country's sea power.
"Compared with their World War I counterparts, submarines [in World War II] now exhibited greater speed, more effective weaponry, sophisticated detection technology and great versatility, and could pursue their victims rather than just lying in wait," wrote historian Gary E. Weir in a U.S. Naval Historical Center publication "Silent Victory 1940-1945."
Submarine warfare took place in both the Pacific and European theaters of war. However, U.S. Navy submarines saw their greatest success against Japanese merchant vessels and warships. Submarines also played humanitarian and special operations roles in the campaign against Japan. In many of the hardest-fought battles of the war, submarine crews rescued downed carrier pilots, including future President George H.W. Bush.
Fleet submarines also delivered troops tasked with special missions. In August 1942, USS Nautilus and USS Argonaut delivered Marine Corps Col. Evans F. Carlson's "Raiders" to Makin Island in the Gilbert chain as a diversion during the Guadalcanal campaign. Subsequently, the two submarines returned to pick up the Marines after they completed their missions to reconnoiter the island and destroy important enemy facilities.
In all, U.S. submarines destroyed 1,314 enemy warships in the Pacific, representing 55% of all Axis power warships lost and a total of 5.3 million tons of shipping, Weir stated.
Out of 16,000 U.S. submariners, the force lost 375 officers and 3,131 enlisted men in 52 submarines, and "although this was a tragic loss, it was still the lowest casualty rate of any combatant submarine service on either side in the 1939-1945 conflict," Weir noted. In the final months of the war, American submarines had difficulty finding targets because the Japanese had virtually no ships left to sink.
Submarines also played an important role in the European theater in the Atlantic Ocean and the Mediterranean Sea, where German U-boats posed a menace against allied shipping, particularly in the early years of the war.
By mid-1943, U.S. advances in sensors and antisubmarine weapons carried by warships convoying merchant vessels greatly reduced the U-boat threat, and much of the submarine force was transferred to the Pacific theater.
After World War II, huge advances were made in submarines: nuclear power enables submarines to remain underwater for long periods of time, and improvements in weaponry include long-range, accurate missiles and torpedoes that can be used against ships, other submarines and even land targets.
Submarines are also used for other missions such as intelligence gathering, minelaying and transport of special operations forces.
Together with long-range bombers and intercontinental ballistic missiles, today’s ballistic missile submarines are the third component of the nuclear triad.