アッツ島
Following the Battle of the Komandorski Islands, Admiral Kinkaid requested a larger force of 25,000 troops to support an assault on Kiska. However, as there were not enough ships to transport such a large division to the Aleutians, Kinkaid suggested that the Americans' objective change from Kiska, which was defended by about 9,000 men, to Attu, which was home to only 500 Japanese. On April 1, Kinkaid received approval from the Joint Chiefs of Staff to execute the operation, codenamed SANDCRAB. The terrain of Attu Island was not hospitable for such an operation – much of the island's landmass not covered in snowy peaks was covered in muskeg, a marshy soil type that is almost impossible to cross by foot. In addition, Attu Island was subject to frequent storms and soupy fogs.