When the Japanese occupied the islands of Attu and Kiska in the Aleutians in Alaska in June 1942, the Allies had to remove them before they could attack the Kuriles. The Aleutians would be the only land battles in North America during World War II. The cold weather and remote location would make resupply of the Japanese garrison difficult, while the Americans would send thousands of highly trained soldiers to attack the outpost that conceivably could threaten Canada and the Western coast of the United States.
When the Dutch Harbor installations were attacked on June 3, 1942, the Americans were not fully prepared for an invasion. But occupying Attu and Kiska was a feint for the Midway operation, with little value other then the tactical goal of drawing the US Pacific Fleet into a major surface engagement. Reading the Japanese codes, the US Navy ignored the landings on Attu and Kiska and went to the defense of Midway, sinking most of the First Air Fleet.
The Americans left the Japanese garrisons in the Aleutians alone until a sufficient fleet with effective land units could be assembled. In January 1943, an attempt to reinforce the Japanese garrisons was repulsed with heavy losses in the Battle of the Komandorski Islands. In March 1943, the US Army 7th Division landed on Attu, and killed all but 30 of Attu's 4700 defenders. The end came in the form of a disorganized, drunken charge, called “Banzai”by the Americans, who heard the word screamed by the advancing Japanese.
In May 1943, the crack 10th Mountain Division and a Canadian force landed on Kiska, and after some sporadic fighting, the Americans found the island deserted. The Japanese had abandoned the island, except for a covering force that committed suicide.
From June 1943 until the end of the war, aircraft from the Aleutians attacked the Kurile Islands, Japan's northernmost possessions. The Aleutians saw cold-weather fighting that was bitter and protracted, and largely ignored by the American public.