Executive Order 11104—U.S.S. Thresher
As a mark of respect to the memory of those who gave their lives when the U.S.S. THRESHER was lost off the Atlantic coast on Wednesday, April 10, 1963 it is hereby ordered pursuant to the provisions of Section 4 of Proclamation 3044 of March 1, 1954 that until sunset on Monday, April 15, 1963 the flag of the United States shall be flown at half-staff on all buildings, grounds and naval vessels of the Federal Government in the District of Columbia and throughout the United States and its Territories and possessions. I also direct that the flag shall be flown at half-staff for the same length of time at all United States embassies, legations, consular offices and other facilities abroad including all military facilities and naval vessels and stations.
JOHN F. KENNEDY
THE WHITE HOUSE,
April 12, 1963
John F. Kennedy, Executive Order 11104—U.S.S. Thresher Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/236067