This was a large Army/Navy base and some Coadt Guard units as well. Some buildings still exsist today. Good read follow link below.
Dear Mr. Jones,
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We searched the National Archives Catalog and located two series in the Records of the Army Staff (Record Group 319) that contain information about Adak Island. We also located the series Unit Histories, 1943-1967 in the Records of U.S. Army Operational, Tactical, and Support Organizations (World War II and Thereafter) (Record Group 338) that includes 27 file units about Adak Island during WWII. In addition, we located the series Station Lists, 1942-1953 in the Records of the Adjutant General’s Office, 1917-1981 (Record Group 407) that has listings for Alaska for 1945 - 1946 (in Boxes 3-4). For access and/or copies of these records, please contact the National Archives at College Park - Textual Reference (RDT2) via email at firstname.lastname@example.org.
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Finally, the U.S. Army Center for Military History has an online publication that details the Army campaigns in the Aleutian Islands during World War II.
We hope this information is helpful. Best of luck with your family research!