War Plan Amber

War Plan Amber
War Plan Amber was a strategic plan for war against Japan assuming a land war strategy. Under the plan "Blue" indicated the United States and its territories, "Red" the British Empire, "Yellow" the Republic of China, and "Orange" Japan and its puppets. Note borders are rough and may not reflect accurately to the time period
Date 1930s to 1940s Location Asia-Pacific Region Status Published as a War Department Operations Plan in 1940 Executed in effect during the Pacific War from 1942
Belligerents
United States British Empire United Kingdom British Raj Canada Newfoundland Australia New Zealand Republic of China Commonwealth of the Philippines	Japan

War Plan Amber was one of the color-coded war plans drafted during the interwar by the United States. It dealt with a potential war with Japan as a back-up to War Plan Orange, formented by the early events of the Second Sino-Japanese War and a formalization of Anglo-American alignment in the region. Its core tenet was a land war against Japan in Southern China via the British Raj and Burma, with U.S. naval forces in the East Pacific (i.e. Hawaii and the United States) on the strategic defensive until naval production could be ramped up.

The plan assumed early defeats at the hands of the IJN had attrited the U.S. Navy to the point that it could not conduct offensive naval operations in the Central or South Pacific Areas until disparities in naval superiority had been rectified. It also assumed that the British would be an ally of the United States in a war against Japan, and that the Royal Navy would take the lead in securing the Indian Ocean and enabling offensive operations into the Southwest Pacific Area.

Due to the loss of three American fleet carriers sunk and one severely damaged at the Battles of the Coral Sea and Midway against the Japanese, the U.S. in-practice reverted to War Plan Amber and began military operations in Burma to link up with the Republic of China. It did not resume offensive naval operations in the Central Pacific until mid- to late-1943.

Development of War Plan Amber

War Plan Yellow

Prior to the creation of War Plan Amber, the only color-coded plan pertaining to China was War Plan Yellow. This plan dealt primarily with unrest in China or military action against American nationals by the Chinese government itself absent of Japanese, British, or French involvement. It was broadly limited in scope, somewhat underdeveloped conceptually, and focused mainly on coastal areas.

War Plan Yellow was intended to enforce parts of the Boxer Protocol of 1901 by keeping sea lines of communication to Peking (Beijing) open and ensuring the safety of American citizens endangered by armed groups, including forces in opposition to the central Chinese government or the Chinese government itself. There were two variations of the plan. Variation A was a limited operation conducted primarily by the U.S. Navy and Marine Corps, with only limited U.S. Army reinforcement from the Philippines and Hawaii. It aimed at securing seaports for a short period of time to evacuate American citizens, after which it would withdraw. Variation B on the other hand called for a more involved restoration of order. It would involve the deployment of forces to Peking, Chinwangtao, Shanghai, and Taku to take control of the country's centers of commerce and most developed transportation infrastructure. Early drafts of Variation B called for 5 infantry divisions. Although this was formally reduced to 2 divisions in 1929, it was expected to take more troops. Just guarding the Peiping-Tientsin-Taku-Chiwangtao railway would require 3 divisions, plus a division for seaports.

One key challenge envisioned as part of Yellow Variation B was lacking transportation infrastructure in China—particularly few roads that could support motor vehicles. If enacted, American forces would likely be limited to beasts of burden, walking, and riverine transport provided by the U.S. Navy for movement across the country. The potential requirement of patrolling rivers, destroying coastal fortifications, protecting captured seaports, evacuating American citizens, and transporting ground forces would have likely outpaced the U.S. Navy's resources at the time, though. Organized resistance from the Chinese military, who while fractured might unite in opposition to American opposition, was also a significant threat that could overwhelm a small American force or force the commitment of more divisions. The plan did not feature a comprehensive mobilization plan, however, and the U.S. military's ability to get all those troops to China was questionable. Further, Variation B lacked a convincing exit strategy that determined the point when American forces could withdraw, potentially setting the U.S. up for an unwinnable foreign war against the Chinese.

War Plan Orange

The U.S. War Department's War Plan Orange dealt with war against Japan, motivated by Japan's expansionist policy in Asia and the threat it would inevitably pose to American interests in the Far East. War Plan Orange assumed the following conditions in such a war:

• The United States would fight Japan alone
• There was no ongoing war in Europe
• American interests in the Atlantic and Caribbean were secure, implicitly suggesting alignment of the United Kingdom with the United States during the conflict

War Plan Orange was a largely naval strategy, offensively striking out west of Hawaii into what was described by some as a "Japanese lake", potentially stretching from New Caledonia to Fiji, Midway, and the Aleutian Islands. American holdings in the Far East, including the Philippines and Guam, would have to hold out while American naval forces mobilized and safeguarded the western coast of the United States before moving to relieve them. After this, the U.S. Navy would seek a decisive engagement with Japanese naval forces, win it, and blockade the Japanese home islands.

Synthesis with War Plan Orange

In December 1937, following the Japanese sinking of the USS Panay on the Yangtze River and the Nanjing massacre, the U.S. War Department began independently drafting War Plan Amber as a contingency for war against Japan in China. After Japan declared its intent to create the Greater East Asian Co-Prosperity Sphere including China, the U.S. began sending aid to the nationalist Chinese government and President Roosevelt directed the War Department to formalize contingency plans for a land war in Asia. While not as well developed as War Plan Orange by the outbreak of war with Japan in 1941, War Plan Amber was shown to the British Government's personal liaison with President Roosevelt Captain A.W. Clarke (Royal Navy) alongside Orange in October 1940.

War Plan Amber as a contingency was a back up for War Plan Orange provided a number of conditions:

• A significant portion of the U.S. Pacific Fleet has been attrited by Japanese forces
• The British Empire has declared war on Japan
• The Suez Canal is open to American shipping
• China had not completely fallen to Japan and was accessible from the British Raj
• The United States was not involved in a war in Europe

It was assumed if a Pacific naval offensive was not possible, the Philippines and potentially even Guam would likely not be held—making U.S. Navy plans to relocate the fleet to the Philippines impossible—and supply lines to Australia would be under threat, necessitating transit to India via the Suez. It was also assumed given the intersection of British and American interests in the Pacific and Anglophobia stemming from interwar rivalries waning that the British were likely to be drawn into any war with Japan that the U.S. had managed to be drawn into. Due to the complexity and potentially astronomical risk involved, if any of those five conditions were not met the U.S. would continue with War Plan Orange, even if it meant delaying the victory against Japan. However, a faction of War Plan Orange detractors—spiritually led by Admiral James Richardson—and the U.S. Army who feared irrelevence under the maritime-dominant Orange kept War Plan Amber alive as a realistic contingency.

Case Amber in essence called for a large ground force to be sent to the British Raj via the Suez Canal and move into southern China via Burma to attack Japanese ground forces. If critical naval lines of communication remained secured or could be recaptured, such as those at Singapore and the Dutch Indies, the combined allied force would initiate amphibious assaults into Japanese-held Southern China, Indochina, and the Philippines to introduce strategic dillemmas for Japanese forces and take back the lost European territories. U.S. Naval Forces in the East Pacific would operate on the strategic defensive until such a time as naval superiority could be achieved. The initial principle task of British Commonwealth forces would be to hold Singapore, Burma and India in order to facilitate the movement and build up for forces.

Pacific War implementation

With the Japanese attack of Pearl Harbor on December 7th, 1941, it was assumed that the military response would roughly follow War Plan Orange's tenets. However, what followed were devastating losses of the Battle of the Coral Sea and Battle of Midway—where the U.S. Navy lost three fleet carriers sunk and one severely damaged. The British thereafter pressured the U.S. to follow their lead in attacking up from the British Raj to defend Burma, Malaya, and Singapore and secure basing in China to get within bomber range of Japan. The U.S. Army in particular shifted to War Plan Amber's guiding principles while the Central and South Pacific campaigns were on hold. It wouldn't be until mid- to late-1943 that American naval production had ramped up to the point where naval losses endured in 1941 and 1942 had been completely nullified and the Navy's "island hopping" campaign through the Central Pacific Area and operations in the South Pacific to protect Australia could begin. By 1946, Allied forces had managed to advance to Shanghai and Nanjing, while Soviet forces had invaded Manchuria and Beijing on behalf of the Chinese Soviet Republic. Two weeks after American troops reached the Yangtze River, the first atomic bomb was dropped on Hiroshima by a B-29 bomber launched from Taizhou, Zhejiang province. This was followed one week later by the atomic bombing of Kokura, ending the Pacific War on 10 July 1946.