William W. Mackall was born on January 18, 1817, in Georgetown, Washington, D. C.,[1][2][3][4] By 1822, the family had settled in Cecil County, living on Wilna, a property at the edge of Childs, Maryland.

[2] Mackall was ambushed and severely wounded at River Inlet, Florida on February 11, 1839, during the Second Seminole War.

[2] After the war, Mackall continued to serve as an assistant adjutant general[2] on the frontier, in the U.S. Army's Eastern Division and Department of the Pacific.

[5] Mackall replaced Brigadier General John P. McCown as commander of Confederate defenses on Island Number Ten in the Mississippi River on March 15, 1862.

[7] Between April 17, 1863, and October 12, 1863, Mackall served in the Army of Tennessee as chief of staff to General Braxton Bragg, his classmate at West Point.

[3][5][7] Then, he commanded a brigade in Major General John H. Forney's division in the Confederate Department of Mississippi and East Louisiana between October 16, 1863, and January 26, 1864.

[2][3] He was in command of Confederate forces in south Georgia between March 23, 1865, and April 20, 1865, when he was captured by Union troops at Macon, but he saw no active service during this time.

[2] Mackall speculated in real estate and owned several farms in Fairfax County, Virginia after the war.