Outline 8 Second World War in the Pacific

7.1 Causes of the Second World War in the Pacific

Long-term causes

Washington Naval Conference

• In 1921–22, nine powers met in Washington to limit warships

  • Five Power Treaty fixed ship ratios at 5:5:3 (US:UK:Japan)

• Japan felt the limits were unfair and left in 1936

Ultra-nationalism

• Military leaders and zaibatsu controlled politics and industry

• As the economy slipped in the 1920s, samurai-style nationalism grew

• Leaders used expansion to secure raw materials and markets

Short-term causes

Great Depression

• Global trade collapsed, and Japan borrowed heavily to rearm

• When finance minister Takahashi cut military spending

  • he was assassinated

Japanese expansion

• A staged explosion at Mukden in 1931 gave Japan a reason to seize Manchuria

• They set up Manchukuo under puppet emperor Pu Yi and left the League of Nations

Sino-Japanese War and US reaction

• Fighting began in 1937 at the Marco Polo Bridge and quickly spread

• The Nanjing Massacre followed, while the US supplied China with loans

War plans

• Army and navy split over attacking the USSR (north) vs. Southeast Asia (south)

• After the 1939 border clash with the Soviets, the “south” plan prevailed

Pearl Harbor

• US oil and steel embargo in mid-1941 cut off 80% of Japan’s fuel

• On 7 Dec 1941, Japan struck Pearl Harbor to knock out the US Pacific Fleet

7.2 Combatants

Allied forces

• Australia grew from a small force in 1939 to over 1 million by 1945

• Britain’s Asian garrisons in India, Burma, and Singapore were under-resourced

• China’s Nationalists and Communists together fought two million Japanese

• The US built its Pacific Fleet from three carriers to 26 by 1945

Japanese forces

• Japan mobilized 24 divisions in 1937 and 50 by 1941, with 3 million men

• Early on they outproduced US aircraft, but by 1943 American output soared

• Most Japanese troops stayed tied up in China, weakening Pacific defenses

7.3 Strategy and Tactics

Japanese war plans

• Japan aimed to seize Southeast Asia for resources, then defend a wide perimeter

• Fortified islands from the Kuriles to Burma were meant to stall US attacks

• As US power grew, Japan had to pull back toward its home islands by 1945

US strategy: Island Hopping

• After Midway, the US bypassed strong islands and captured weaker ones

• Each captured island became a base for air strikes on the next target

Strategic bombing and commercial warfare

• From Saipan, B-29s began firebombing Japanese cities in 1944–45

• US submarines sank most Japanese merchant ships, cutting off supplies

Fighting in the Pacific

• The vast ocean made carriers and long-range planes essential

• Amphibious landings needed tight air and naval cover to succeed

7.4 Operations

Japanese advance – Philippines, Singapore, Hong Kong

• In Dec 1941, Japan quickly took Malaya, Singapore, and Hong Kong

• Manila fell after Japanese planes destroyed Allied aircraft on the ground

Guadalcanal

• US Marines seized Henderson Field in Aug 1942

• Six months of fierce combat cost the US 2,000 dead and Japan 20,000

The Marshall and Marianas Islands

• Kwajalein and Eniwetok fell in early 1944

• Saipan and Tinian then came, bringing Japan within B-29 range

The Philippines

• Leyte landings began MacArthur’s return in Oct 1944

• Manila was liberated in March 1945 after brutal urban fighting

Burma

• British-Indian forces and Stilwell’s Chinese-American command attacked from India and China

• Rangoon fell in May 1945, reopening supply lines to China

The war at sea

• Midway (June 1942): US codebreaking allowed a surprise attack that sank four Japanese carriers

• Leyte Gulf (Oct 1944): Japan’s last fleet action failed, but kamikaze tactics appeared

The air war

• Bombing Campaign: Fire raids from late 1944 destroyed much of Japan’s cities

• Manhattan Project: The US tested its first bomb in July 1945, then dropped atomic bombs on Hiroshima and Nagasaki in August

7.5 Post-war Consequences

Democratization of Japan and US occupation

• MacArthur’s occupation (1945–52) disbanded Japan’s military and rewrote its constitution

• Land and labor reforms broke up large estates and empowered unions

Cold War

• Japan became a key US ally against communism in Asia

• The 1951 Peace Treaty restored sovereignty but kept US bases in place

Imperialization and decolonization

• Japan lost its former colonies, and Western empires in Asia unraveled

• Korea, Indochina, Burma, and others gained independence by the early 1950s