Umnak (; ) is one of the Fox Islands of the Aleutian Islands. With of land area, it is the third largest island in the Aleutian archipelago and the 19th largest island in the United States. The island is home to a large volcanic caldera on Mount Okmok and the only field of geysers in Alaska. It is separated from Unalaska Island by Umnak Pass. In 2000, Umnak was permanently inhabited by only 39 people and by 2010, around 18, placing the settlement of Nikolski in difficulty and its school was closed. History The earliest known settlement on Umnak Island is at Anangula and is 8,400 years old. Anangula was later abandoned and the Sandy Beach site became occupied, along with Idaliuk and Chaluka. Most of the early settlements on Umnak were located along the streams. A major geologic event was the cutting of strand flats during the Hypsithermal period, about 8250 to 3000 years ago, which led to a greater natural food supply on the island for the settlers. Umnak Island was first reached by independent Russian fur traders in the 1750s. Abuses by the Russians led to an alliance among Aleuts in the Fox Islands. During the winter of 1761–1762, the crews of four Russian ships were massacred. This included one entire crew on Umnak which was completely wiped out. Russian traders responded with a scorched-earth campaign in 1764 that essentially ended the Aleuts' independence. The modern history of Umnak Island is linked to the military bases established by the United States during World War II. The purpose of the forward air bases in the Aleutian Islands was not only to defend the Dutch Harbor, but also to launch attacks against the Japanese mainland. The US Navy considered Umnak as exclusive and their own. They created a camouflage in the "Blair Fish Packing Co," to build airports and bases to be used by the US Army Air Force during World War II. After getting clearance from General DeWitt, General Buckner built airbases at Umnak (eventually known as Fort Glenn) and at Cold Bay. By the time the Japanese attacked in the summer of 1942, the US garrison at Umnak had a combined strength of 4000, including engineer companies complemented by infantry, as well as field and antiaircraft artillery units. The Japanese planned to attack and capture the island in June to maintain aerial patrols over North Pacific waters.