January 31, 1862
Ordered, That all the disposable force of the Army of the Potomac, after providing safely for the defense of Washington, be formed into an expedition for the immediate object of seizing and occupying a point upon the railroad southwestward of what is known as Manassas Junction; all details to be in the discretion of the General in Chief, and the expedition to move before or on the 22d day of February next.
A. LINCOLN.
Abraham Lincoln, Executive Order—Special War Order No. 1 Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/202439