After the declaration of war, General Order 36 of May 7, 1898 approved the organization of eight "army corps," each of which was to consist of three or more divisions of three brigades each.

Major General John J. Coppinger was named as commander of Fourth Army Corps, which was to assemble at Mobile, Alabama.

In the meantime, the First Division, under the command of Brigadier General Theodore Schwan, was transferred to Miami on June 20.

[3] On August 11, with the end of the war in sight, the corps was transferred again, to Huntsville, Alabama.

The Fourth Army Corps was "discontinued" on January 16, 1899; its strength on the last day of 1898 was 545 officers and 13,337 enlisted men.