May 31, 1865
Tomorrow, the 1st of June, being the day appointed for special humiliation and prayer in consequence of the assassination of Abraham Lincoln, late President of the United States, the Executive Office and the various Departments will be closed during the day.
ANDREW JOHNSON,
President of the United States .
Andrew Johnson, Executive Order Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/202157