The West Coast War

 The Japanese did indeed attack the West Coast of the United States during World War Two. The most notable of these incidents was the naval bombardment of Ellwood, near Santa Barbara, California, which targeted the Ellwood Oil Field and caused minor damage to the facility. This occurred on February 23, 1942.

The military installation at Fort Stevens in Oregon was also shelled by the Japanese submarine I-25 on June 21, 1942, although the bombardment caused only minimal damage. In addition, Japanese forces occupied two of the Aleutian Islands, Kiska and Attu, in June 1942, shortly after the Battle of Midway. The occupation was intended in part to protect Japan’s northern flank and extend its defensive perimeter. The Japanese landing on Attu marked the first time that U.S. territory had been occupied by a foreign power since the War of 1812.

So why did the Japanese not go any further?

The defeat of the Japanese carrier force at Midway severely curtailed further Japanese expansion in the Pacific and shifted the strategic initiative toward the United States. However, let us play devil’s advocate for a moment and assume that the Imperial Japanese Navy had emerged victorious at Midway, defeating Admirals Nimitz, Spruance, and Fletcher.

Such a victory would have significantly altered the balance of power in the Pacific in Japan’s favor. It could have delayed or seriously complicated the American counteroffensive, while a weakened U.S. Pacific Fleet would have made the defense of Hawaii considerably more difficult. With a stronger position in the Central Pacific, Japan might have been able to launch additional attacks against the American West Coast and, more importantly, impose a greater naval threat against the United States while the American fleet was rebuilding.

Even in this alternative scenario, however, it is very unlikely that the United States would have sued for peace. The American industrial base and population remained intact, and the continental United States was never seriously threatened with invasion. Japan might have gained time and territory, but defeating the United States outright would have been an entirely different matter.

As for a full-scale frontal attack on the West Coast, that possibility was exceedingly improbable. The planning, shipping, manpower, and logistical requirements would have been enormous—on a scale that would have dwarfed even the Allied preparations for D-Day. The Pacific Ocean presented a formidable geographic barrier, and Japan simply lacked the manpower and industrial capacity necessary for such an undertaking.

Japan's military commitments elsewhere made the prospect even less realistic. Its forces were already heavily engaged in China and across the enormous territories it had conquered in Southeast Asia and the Pacific. Its defeat by Soviet and Mongolian forces at Khalkhin Gol in 1939 had also demonstrated the difficulties of conducting a major land campaign against the Soviet Union. These considerations contributed to Japan's decision to pursue a southern strategy rather than open a second major front against the Soviet Union—much to Adolf Hitler's frustration.

Invading the American mainland would have been an even more daunting proposition. This was fundamentally different from attacking and occupying American positions in the Philippines, where Japan could operate from bases relatively close to its existing sphere of control.

By 1942, Japan was already heavily committed across a vast area, having expanded its control over the Malay Peninsula, Singapore, Hong Kong, the Dutch East Indies, the Philippines, French Indochina, Burma, and numerous Pacific islands. Its more realistic objective after a hypothetical victory at Midway would therefore have been to consolidate its gains, suppress Allied resistance, and establish a defensive perimeter strong enough to contain or delay an eventual American counteroffensive.

Additional raids against the American West Coast were conceivable. A sustained campaign aimed at invading and conquering the continental United States was not.

Japan's best hope was therefore not to conquer America, but to make the cost of defeating Japan sufficiently high that Washington might eventually reconsider its objectives. In reality, however, Japan's strategic position deteriorated rapidly after Midway, and the United States was able to bring its enormous industrial capacity to bear. Any Japanese strategy based on permanently holding off the United States was ultimately doomed.