Submarine History Today - Japanese Submarine Shells U.S. Soil
In the only direct attack on U.S. military installation on the mainland by any Axis power during World War II, the Japanese submarine I-25 fired 17 shells at Fort Stevens, Washington on this day in 1942.
The fort, originally built during the Civil War, protected the mouth of the Columbia River where it entered the Pacific Ocean. The Japanese Navy apparently believed that there was an American submarine base at the fort (there wasn't)
The attack caused only minimal damage. One round severed some telephone cables, and another damaged the backstop at the base's baseball field. The total cost of the repairs has been estimated by at least one historian to be about $20.
I-25 also carried out the only aerial attack on the U.S. mainland, the so-called "Lookout Air Raid" on September 9th, 1942. This attack, also carried out against the Oregon coast, also caused minimal damage.
Likely, these attacks were carried out with the hope of creating panic and harming American morale, rather than out of any hope of real damage.
I-25 was sunk by USS Patterson (DD-392) off the New Hebrides (now Vanuatu) on August 25th, 1943.