Special Engineer Detachment
| 9812nd Technical Service Unit | |
|---|---|
 Manhattan Project Shoulder Patch | |
| Active | 22 May 1943–15 August 1947 |
| Country | United States |
| Branch | United States Army Corps of Engineers |
| Size | 6,032 on 1 December 1945 |
| Garrison/HQ | Los Alamos Laboratory, Oak Ridge |
| Engagements | |
The Special Engineer Detachment (SED) was a U.S. Army program that identified enlisted personnel with technical skills, such as machining, or who had some science education beyond high school, to meet the needs of the Manhattan Project during World War II. SED personnel included the Clinton Engineer Works, Hanford Engineer Works and Los Alamos Laboratory. SED personnel began arriving at Los Alamos in October 1943, and by August 1945, 1,800 worked there. They worked in all areas and activities of the Laboratory, including the Trinity Test, and served overseas on Tinian in support of the atomic bombing of Hiroshima and Nagasaki and in the Pacific with the Operation Crossroads nuclear test series at Bikini Atoll in 1946.