WW2 in Pacific: Practices of War and the Impact on the Outcome Notes

WW2 in the Pacific: Practices of war and their effect on the outcome

Key Questions

1. What were the relative strengths of the combatants in WW2 in the Pacific?
2. What were the strategic developments of the war?
3. What role did technological developments and the mobilisation of human and economic resources play in the outcome of the war?

1. The combatants of the war

British Forces in the Asia-Pacific Region

1. Britain’s early military presence in the Pacific was focused on territories like India, Burma, and Singapore, with additional garrisons stationed in Hong Kong and other minor holdings.
2. The Royal Navy was primarily engaged in the Atlantic and Mediterranean due to the strategic importance of defending Britain’s supply routes after the war began in Europe.
3. The defence of Burma relied heavily on the British Indian Army, which eventually reached around 30,000 troops, though they were often under-equipped and lacked sufficient training or support.
4. The retreat from Burma was devastating: only about 17,000 soldiers managed to return to India.
5. Singapore’s defence also depended largely on Indian troops, with the garrison eventually reaching a strength of over 130,000.
6. When Singapore fell to the Japanese, more than 80,000 British and Commonwealth troops were taken prisoner following General Percival’s surrender.

Chinese Resistance Against Japan

1. Both Chinese Nationalist forces under Jiang Jieshi (Chiang Kai-shek) and Communist forces led by Mao Zedong fought against nearly 2 million Japanese soldiers during the war.
2. Jiang’s army had a core of about 230,000 effective troops, but was spread thin across the country with an additional 300 poorly led, ill-equipped divisions of limited combat ability.
3. Mao’s Communist forces expanded during the war to around 400,000 fighters, including both conventional soldiers and guerrilla units.

United States

1. Over the course of the war, the U.S. Army committed 20 divisions specifically to combat operations in the Pacific theatre.
2. The U.S. Marine Corps expanded significantly, growing to six divisions with a total strength of approximately 485,000 personnel.
3. The Marines also developed their own air support units, giving them greater independence and operational flexibility.
4. As of October 1941, the U.S. Pacific Fleet consisted of:
   1. 3 aircraft carriers
   2. 9 battleships
   3. 8 cruisers
   4. 40 destroyers
5. By the end of the war, the Pacific Fleet had undergone massive expansion, reaching:
   1. 23 battleships
   2. 65 cruisers
   3. 26 fleet carriers

Australia

1. At the start of World War II, Australia’s navy was small despite the vast coastline it needed to protect, its main warships included just six cruisers of varying sizes.
2. The standing army consisted of only around 3,000 professional soldiers, supported by about 80,000 reservists with uneven levels of training and readiness.
3. The Royal Australian Air Force had a limited fleet of roughly 250 aircraft at the outset of the war.
4. By the war’s end, Australia’s military had grown dramatically to over 1 million personnel.
5. Australian forces served in most of the major battle zones during the conflict and endured approximately 50,000 casualties.

Japan

1. At the start of the invasion of China in 1937, Japan’s army fielded approximately 24 divisions and had access to around 5,000 aircraft.
   1. Through a combination of conscription and military indoctrination, the size of the army expanded to 50 divisions by 1941.
   2. By that same year, Japan’s army and navy collectively operated 130 air squadrons, each with 12 to 24 aircraft.
2. Just before the attack on Pearl Harbor, Japan could call upon over 3 million military personnel, though their level of training varied widely.
3. In 1939, Japan was producing more than 4,400 aircraft per year, nearly double the U.S. output at that point.
   1. However, Japan’s aircraft industry saw only modest growth by 1941, while U.S. production surged to over 26,000 aircraft annually, thanks to Allied demand and full-scale mobilisation.
4. By the end of the war:
   1. Japan reached an output of about 11,000 aircraft per year.
   2. The United States produced nearly 50,000 aircraft annually.
5. Despite the size of its military, Japan’s forces were overstretched throughout the conflict. China remained the main focus of Japanese military efforts:
   1. By 1945, approximately 1.8 million Japanese soldiers were stationed in China.
   2. This left fewer troops available to defend Japan itself as the Allies advanced toward the home islands.

2. Strategic developments of the war

Japanese Expansion and Initial Successes (Dec 1941 – Mid-1942)

1. Japan pursued a rapid offensive to seize territory rich in oil, rubber, and minerals to support its war economy, particularly in Southeast Asia and the Pacific.
2. Simultaneous attacks were launched on:
   1. Pearl Harbor – disabling the US Pacific Fleet’s battleships.
   2. Philippines, Malaya, Hong Kong, Guam, Wake Island, Dutch East Indies – aiming to establish a self-sufficient “Greater East Asia Co-Prosperity Sphere.”
3. Japan expected to cripple the US quickly and force a negotiated peace before American industrial power could be fully mobilized.
4. Early victories gave Japan control over a vast empire stretching from Burma to the Solomon Islands.

Shift in Initiative: Coral Sea and Midway (May–June 1942)

1. Battle of the Coral Sea (May 1942):
   1. First naval battle where opposing ships never saw each other, fought entirely with carrier-based aircraft.
   2. Tactical draw but strategic US-Australian victory as it halted Japan’s advance on Port Moresby (Australia).
2. Battle of Midway (June 1942):
   1. US intelligence cracked Japanese codes and prepared an ambush.
   2. US Navy sank four Japanese aircraft carriers, the core of their naval air power.
   3. Marked the decisive turning point, Japan lost the strategic initiative and moved to a defensive posture.

The Guadalcanal Campaign (Aug 1942 – Feb 1943)

1. First major Allied land offensive in the Pacific, aimed to prevent Japan from threatening supply lines to Australia.
2. Brutal jungle warfare with high casualties on both sides.
3. US Marines initially landed unopposed, but Japanese reinforcements prolonged the battle for six months.
4. Naval battles around the island further degraded Japanese sea power.
5. Success here confirmed that Japan could be defeated in ground combat and set the stage for further offensives.

Island Hopping Strategy (1943–45)

1. Rather than retake every Japanese-held island, US forces bypassed strongholds, capturing strategic islands to build airfields and naval bases.
2. Each island taken allowed the Allies to extend air superiority and support the next operation.
3. Major examples:
   1. Tarawa (1943) – heavy US Marine casualties proved the tenacity of Japanese defence.
   2. Kwajalein, Eniwetok, Saipan, Tinian, and Guam – placed Japan within range of strategic bombing.
4. The strategy was designed to minimize Allied casualties while steadily strangling Japanese control in the Pacific.

The Philippines Campaign and Battle of Leyte Gulf (1944–45)

1. General MacArthur returned to the Philippines, fulfilling his 1942 promise.
2. Battle of Leyte Gulf (Oct 1944):
   1. Largest naval battle in history.
   2. Japanese navy attempted to prevent US landings but suffered massive losses, including most of its remaining capital ships.
   3. Severed Japan from oil supplies in Southeast Asia.