These lists describe the territorial and field commands of the Union and Confederate armies, 1861 to 1865.
Territorial organisations are listed for Military Divisions, Departments, Districts, Sub-Districts and equivalents. Field organisations are listed for Armies, Army Corps, and equivalents. The establishments, transfer, and discontinuation of organisations are accompanied with the dates of commanders.
The Chronologies make it possible to trace the evolution of commands pre-war, during the war and post-war periods. A particular organisation will be listed many times as its name and its superior or subordinate organisations changed. These are grouped into theatres of war for convenience with an overview.
The Lists make it possible to see the evolution of a single organisation, tracing its changes of names, and commanders, presented as a single entity.