Defense of the Americas: The U.S. Army Campaigns of World War II

This map shows how the U.S. was divided into defense areas. The Western Defense Command was the one in which persons of Japanese ancestry were evacuated from the West Coast and eventually sent to internment camps in the general center of the U.S.

“Japanese incendiary balloon over the Pacific, where prevailing winds propelled them toward the west coast of the United States. (DA photograph)”

The Japanese send around 9000 of these balloons over to the U.S. The program, for them, turned out to be a failure. Probably 90% or more of these balloons never made it to the U.S. Of those that did, some were shot down; others ended up in one forested area or another, but failed to spark any major fires like the Japanese had hoped. The U.S. government kept a tight lid of information about the balloons, trying to stop the Japanese from finding out anything about their success in getting them to the U.S. There were some people killed when they got too near a balloon that had crashed, but those were the only casualties of the entire balloon program.

From the booklet: “It appeared in January 1942 that the defenses of the west coast had been breached by the attack on the U.S. Pacific Fleet and the Hawaiian Islands. Two weeks of panic followed the Pearl Harbor attack as anxious citizens made many erroneous “sightings” of the Japanese fleet. The Army rushed antiaircraft units to defend the California oil industry; critical aircraft plants at Los Angeles, San Diego, and Seattle; and naval shipyards in the Puget Sound, in Portland, San Francisco, Los Angeles, and San Diego. By the end of February almost 250,000 troops had arrived to defend vital installations on the west coast, a task for which Army ground combat units were neither intended nor trained. General Marshall’s chief concern was that the public fear of imminent invasion would freeze this force in a perimeter defense of the coast at a time when these regulars were desperately needed to train the citizen army being mobilized by the Selective Service System. Within six months, however, the demand for such defenses abated as Japanese intentions became clearer. If there had ever been a risk of west coast invasion, it disappeared after the Battles of the Coral Sea (6–8 May 1942) and Midway (3–6 June 1942), which crippled the Japanese aircraft carrier force that would have been essential to an attack on the American mainland. After the results of Midway became clear, the Army began to stand down its defenses on the west coast, reassigning its Air Forces units and antiaircraft forces to other duties. “

The fear of an invasion was one of the reasons given for the evacuation of persons of Japanese ancestry to the internment camps, although racial prejudice and economic jealous were the actual main reasons.

As I have noted elsewhere on my site, there were a small number of Japanese attacks that involved the North American Pacific Ocean coast. Form the booklet: “The west coast actually saw a limited amount of warfare. Submarines of the Japanese 6th Fleet performed reconnaissance and struck the sea lines of communication. Around the middle of December 1941, nine submarines arrived in American waters for the start of what was to be eight months of operations. Four of these boats eventually made attacks on coastal shipping, sinking two tankers and damaging one freighter. On 23 February 1942 the submarine I–17 surfaced near Santa Barbara and used its deck gun to fire thirteen 5.5-inch shells into oil installations, although with negligible damage. On the night of 21–22 June 1942, a submarine rose to the surface at the mouth of the Columbia River in Oregon and fired about a dozen 5.5-inch shells at Fort Stevens, a coast artillery fort. Militarily insignificant, that attack marked the first time since the War of 1812 that a foreign enemy had fired on a military installation in the continental United States. In early September 1942 the final Japanese submarine attack on the American coast during the war took place in reprisal for the Doolittle raid on Tokyo the previous April. The I–25, which carried a float plane, launched its aircraft off the Oregon coast on the 9th of the month. The airplane dropped an incendiary bomb on a forested mountain hill near Brookings, starting a small forest fire that local authorities quickly extinguished. The I–25 then sank two tankers before leaving for Japan.”

The above refers to the Santa Barbara attack, the Fort Stevens attack, and the plan that bombed the Oregon forest. This was basically the high water mark as far as Japanese military incursion into U.S. territory went.



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