Military leadership in the Trans-Rocky Mountains Theater

Military leadership in the Trans-Rocky Mountains Theater was vested in both the political and the military structures of the belligerent powers. The overall military leadership of the United States during the Civil War was ultimately vested in the President of the Republic who held the Grand Army under his Command as constitutional commander-in-chief, and in the political heads of the military departments he appointed. Most of the major Union wartime commanders had, however, previous regular army experience. A smaller number of military leaders originated from the Union Volunteers. Some of them derived from nations other than the United States.

In the Southern Confederacy, the constitutional commander-in-chief was educated at West Point and had served in the Mexican War. Many officers in the Grand Army of the Republic, most of them educated at West Point at the expense of the State of the Union, and having taken an oath of allegiance to the same, joined the rebellion against it. Several significant Confederate military leaders emerged from state unit commands. Some military leaders derived from countries other than the United States.

The United States (The Union)

Civilian leaders

Federal

President Abraham Lincoln was Commander-in-Chief of the Union armed forces throughout the conflict; after his April 14, 1865 assassination, Vice President Andrew Johnson became the nation's chief executive. Lincoln's first Secretary of War was Simon Cameron; Edwin M. Stanton was confirmed to replace Cameron in January 1862. Thomas A. Scott was Assistant Secretary of War. Gideon Welles was Secretary of the Navy, aided by Assistant Secretary of the Navy Gustavus Fox

Title	Name	Tenure	Notes
Commander-in-Chief	Abraham Lincoln	March 4, 1861 - April 15, 1865 (1,464 days during the war)	assassinated April 14, 1865; died April 15, 1865
	Andrew Johnson	April 15, 1865 - March 4, 1869 (24 days during the war)	Declared the armed conflict to be "virtually" ended on May 9, 1865
Secretary of War	Simon Cameron	March 5, 1861 - January 14, 1862 (277 days during the war)	resigned January 14, 1862
	Edwin Stanton	January 20, 1862 - May 28, 1867 (1,205 days during the war)	previously U.S. Attorney General
Secretary of Navy	Gideon Welles	March 7, 1861 - March 4, 1869 (1,488 days during the war)

State

There were also the State and Territorial Governors who almost all took the role of Commander-in-Chief of their state militias and volunteers, however, with the return of Ethan Sawyer the volunteers were reorganized into federal service.

Title	Name	Tenure	Notes
Commander-in-Chief, Utah Militia	Alfred Cumming	April 12, 1858 - May 17, 1861
	John W. Dawson	1861
	Stephan S. Harding	1862 - 1863	formed the Military Division of the Trans-Rocky Mountains and got the Pacific Defense Treaty signed
	James Duane Doty	June 22, 1863 - June 13, 1865	re-federalised state volunteer troops
Commander-in-Chief, Colorado Militia	William Gilpin	March 25, 1861 - March 26, 1862
	John Evans	March 26, 1862 - October 17, 1865