Causes of US entry into world war 2?

Answer 1

The immediate cause of US entry into WWII was of course the attack by the Japanese Navy on the Pacific Fleet of the US Navy, in its anchorage within the Navy base at Pearl Harbor, in the (then) US territory of Hawaii, on Decmber 7, 1941. The following day President Franklin Roosevelt addressed a joint session of congress and demanded a Declaration of War against the Empire of Japan, which congress immediately voted for, with but one dissenting vote. On December 11, Germany and Italy declared war on the US.

With regard to Japan the US had been critical of Japan's aggression against neghboring states since the Japanese invasion of China in 1937. (This followed a Japanese action in 1931 manufacturing an incident as a pretext for waging war against Manchuria, and after winning that war setting up a Japanese puppet state in Manchuria, which was renamed Manchukuo). In 1937, there were small US Naval vessels, gunboats, operating on the rivers of China. China had almost no roads and the river system, for thousands of years, was the means of transportation in China, and most major Chinese cities and the bulk of the Chinese people were living beside these great rivers. There were gunboats of several other nations there on the rivers as well. This had been the situation in China since around 1900. One of the US gunboats, the USS Panay, was bombed and sunk by Japanese airplanes in 1937, as she was tied up in the river alongside four US oil tankers, about 20 miles from Shanghai, which the Japanese were in the process of conquering. Several US sailors were killed in this attack against a US Navy ship, clearly marked with large American flags painted on awnings stretched over the deck. The Japanese airplanes machine gunned survivors in the water after the ship sank. The Japanese government apologized, paid reparations, and claimed it was a "mistake", so war was averted at that time. But the US continued to pressure the Japanese to stop their incursion and withdraw from China. The militarists running Japan were committed to a vision of Asia dominated by Japan, with the European and American Imperialists expelled, and were unable to back away from their plans for conquest. Japan became an ally of Germany and Italy in 1940, an alliance Germany probably sought because they hoped, when Germany went to war with the Soviet Union (Russia) Japan would join in and attack Russia from its Pacific coast, and repeat the beating the Japanese had given the Russians in the Russo-Japanese War of 1905. In 1940 Germany conquered France and installed a puppet government there. This puppet government then "invited" the Japanese to occupy the French colony of Indochina (today this is Vietnam, Laos and Cambodia, or Kampuchea). The Japanese occupied French Indochina in the summer of 1941, and this move provoked the US to cut off the sale of oil to Japan. Japan has no oil of her own, and to that point had relied on oil bought from the US to fuel her war machine. Oil is the lifeblood of a modern military. President Roosevelt never meant the oil embargo to be final and absolute - he wanted leverage, to be able to extract concessions from the Japanese. Of this the Japanese appeared to be unaware. The Japanese had only an 18 month supply of oil on hand, so it seemed they must either knuckle under to US pressure, stop conquering their neighbors, and give up the cherished dream of the "Greater East Asia Co-Prosperity Sphere" (with Japan as "First Among Equals"), or else come up with another source of oil. There was plenty of oil in the Dutch East Indies (Malaysia today). The Dutch were another European nation just conquered and occupied by Nazi Germany, and this was their colony. The Japanese decided to sieze the Dutch East Indies to secure this oil supply for themselves. But they worried that US military forces in the Philippine Islands might interfere. The Philippines were a US possession since 1898, taken from Spain in the Spanish-American War. So the Japanese decided to grab the Philippines at the same time as they took the Dutch East Indies. The Japanese warlords did not understand that, unlike themselves, at that time at least a US president could not take the US to war whenever he wanted to, and that no matter how many of some other nation's colonies Japan conquered the US people were not going to support a war with Japan over that issue alone. So the Japanese decided to do the one thing that would GUARANEE war with the US, by making a preemptive attack on the US, in its territory of the Philippines. The great Japanese Naval leader, Admiral Yamamoto, decided that as long as they Japanese were going to attack the US in the Philippines, they might as well go ahead and try to knock out the main naval strength of the US in the Pacific, which led to the attack on Pearl Harbor.

Regarding Germany the US had likewise been critical of Nazi aggression and conquest of her neighbors. After 1940, Germany had beaten all enemies except Great Britain, and Great Britain was the only nation at war with Nazi Germany. The US sold, then basically gave supplies to the British to continue the fight. German submarines tried to sink all the ships carrying these supplies from the US to the UK. To combat the subs the ships sailed in groups called convoys, escorted by sub-chasing ships of the British Royal Navy. Then, the US Navy began doing the escorting to the middle of the Atlantic, where British sub-chasers met the convoys and took over. This led to German submarines torpedoing two US Navy sub-chasing destroyers, one of which sank, with heavy loss of life in both incidents. So there was an undeclared naval war between the US and Germany in the autumn of 1941, before Germany declared war on the US, after the US declared war on Japan in response to Pearl Harbor.

Answer 2

the Japanese bombing of peal horbor in Hawaii