War in the Pacific: The Pacific Offensive
The Silent Service: Submarines in the Pacific
A U.S. submarine commander observes
enemy ships through a periscope. American subs inflicted significant
losses to Japanese shipping during the Second World War.
Among the U.S. Navy's deadliest and arguably its most
effective weapons were its submarines. The unrestricted submarine
warfare during the Second World War in the Pacific knew no bounds, no
limits concerning the sinking of Japanese ships. Shrouded in secrecy,
the "Silent Service" depended on stealth for its success and
resourcefulness to counter Japanese countermeasures. The United States,
early on, recognized the importance of the Pacific sea routes to the
Japanese. A strong merchant marine was essential to Japan's wartime
economy. Its ships imported vital oil, iron ore, bauxite, rubber, and
foodstuffs; Japan sent by ships armaments and ammunition, aircraft, and
soldiers to support the forces committed to defeating the ABDA powers
and, later, following the Midway and Guadalcanal battles, with the
intent of making the Allied counteroffensive so costly in lives that the
soft Americans would opt for peace. The Pacific Ocean was the lifeline
to Japan's imperial success; sinking ships would cripple the commerce of
the Rising Sun.
Postwar records compiled by the Joint Army-Navy
Assessment Committee indicate Japan lost 686 warships of 500 gross tons
(GRT) or larger, 2,346 merchantmen, and a total of 10.5 million GRT to
submarines during 1,600 war patrols. Only 1.6 percent of the total U.S.
naval manpower was responsible for America's success on its Pacific high
seas; more than half of the tonnage sunk was credited to U.S.
submarines. The tremendous accomplishments of American submarines were
achieved at the expense of 52 subs with 374 officers and 3,131 enlisted
volunteers lost during combat against Japan; Japan lost 128 submarines
during the Second World War in Pacific waters. American casualty counts
represent 16 percent of the U.S. operational submarine officer corps and
13 percent of its enlisted force.
During the early years of the Pacific war, submarine
warfare was an inexact and faulty operation. Prior to America' sentry
into World War II, the United States was a signatory to numerous
international treaties decrying unrestricted submarine warfare against
merchant shipping. Allied merchant shipping in the Atlantic Ocean took a
merciless beating from German U-boats, despite President Franklin D.
Roosevelt's policies that by June 1940 were aimed at providing Britain
and her allies the tools of war. By the autumn of 1941, following the
stationing of U.S. Marines in Iceland, lives were lost as U.S.
destroyers were attacked by German U-boats.
A typical American submarine, the U.S.S.
Salmon (SS 182), survived one of the most severe enemy depth
charge attacks of WWII.
America's policy on submarine warfare changed
following the Pearl Harbor attack on December 7, 1941. Other problems
had to be overcome, as well, including the belief that aircraft, sonar,
and depth charges would make the submarine vulnerable to enemy naval and
air attack. Peacetime submarine commanders' strategies, in retrospect,
were also archaic: attack from deep submergence with sonar. Considered
overly hazardous were day and night periscope attacks, as well as night
surface attacks; operating within 500 miles of an enemy air base was
considered suicidal. The devastating attacks by U-boat wolfpacks had
demonstrated the fallacy of these concerns.
A final, but major, obstacle that struck at the U.S.
submarine forces' Achilles Heel early in the war was defective
torpedoes. Developed during peacetime, but never fully tested against
targets, torpedoes were considered the most lethal weapon of the U.S.
naval arsenal. Swift and silent, these underwater missiles could sink or
disable wartime and merchant shipping. The torpedo had two exploders,
one that detonated on contact with an enemy ship, and a secret "magnetic
exploder" that would detonate beneath the keel of a ship without
contact. But, as America's submarine force steadily increased the usage
of torpedoes during the early phases of the war, it was discovered that
the torpedoes would run much deeper than designed, thus making the
magnetic exploder inoperative. It was further discovered that the
magnetic exploder was often defective, exploding well before reaching
the target. Corrections were made 21 months after America's entry into
the war, and, despite orders to the contrary by officers of the Torpedo
Bureau, submarine captains discontinued use of magnetic exploders.
A Japanese ship sinks to the bottom in
this photograph taken through the periscope of an American
Despite the initial faults of America's submarine
force, there was optimism. For example, between 1941 and 1945, U.S. Navy
codebreakers deciphered Japanese sailing dates, courses, speeds, and
routes of naval convoys and formations, unbeknownst to the Japanese.
This information was supplied to the U.S. submarine force, which would
lie silently in wait for unsuspecting ships. By 1943, 22 Japanese
warships and 296 merchant ships would be sent to the bottom, due to
workable torpedoes and changed underwater tactics.
Increased submarine proficiency, founded on an
all-volunteer service (submariners made fifty percent extra pay), new
long-range fleet type models, and the successes of the U.S. Navy
codebreakers, by August 1944, found the "Silent Service" inflicting
prohibitive losses on the Emperor's merchant marine, scoring key
successes against Japanese warships that insured victory in the Battle
of the Philippine Sea, and a blockade of the home islands that was
strangling the Japanese economy.
Acquiring this newly found naval status had been an
arduous and difficult affair. Surviving vessels of America's Asiatic
Fleet were redeployed and moved from Manila Bay to first Darwin and then
Freemantle, Australia, in early 1942 and a new commander, Admiral
Charles Lockwood, placed in charge. Lockwood's energy and enthusiasm
revamped submarine tactics, to be employed by the newer subclasses. This
was dictated because Japanese submarines had scored successes. On
September 15, 1942, the Japanese submarine I-19, firing a spread
of four torpedoes, sank the aircraft carrier Wasp and seriously
damaged North Carolina, one of Uncle Sam's newest and most
powerful battleships. The previous month, the aircraft carrier
Saratoga had been torpedoed and put out of action for months.
These losses, along with that of Wasp's sister Hornet, to
air attack on October 27, seriously crippled U.S. naval airpower in the
weeks that the battle for Guadalcanal hung in the balance. The situation
for Lockwood and America's submariners was slowly improving by late
1942: U.S. subs in 1942 sank 180 Japanese ships for a total of 725,000
GRT; yet Hitler's U-boats sank 1,160 Allied ships of more than 6 million
During 1943, Lockwood assumed control of ComSubPac
(Command of Submarines, Pacific) in Pearl Harbor. The Central Pacific
campaign was mapped out by command headquarters for the assaults on
Tarawa and Makin, and submarines played a pivotal role. The German
strategy of "wolfpacking" was adopted. It called for coordinating
submarine attack groups during 1943. More submarines, of larger size and
firepower, were being built in American shipyards. New torpedo designs
added the necessary punch for U.S. subs to eventually penetrate the once
forbidden Sea of Japan. By year's end, American sub improvements had
netted a total of 1.5 million GRT sunk. Eighty-six American subs had
also rescued 380 downed aviators from Pacific waters.
American submarines flexed their naval might
following the recapture of Guam in July-August 1944. U.S. subs based on
Guam and Saipan imposed a virtual blockade against Japan. Few ships
entered or left Japanese waters without being attacked or sunk by
submarines. Japan ran out of oil for her naval armada, gasoline for
aircraft and tanks, steel and aluminum for industry, and food for her
people. By August 1944, the sea war was no longer in doubt-three of
Japan's remaining five fleet carriers had been sunk, and Japan's navy
ceased thereafter to be a factor in the outcome of the war.
U.S. submarines return to port after a
successful patrol, as a PBY aircraft scouts for enemy ships at upper