XVIII Corps (Union army)

It was initially composed of five divisions stationed in North Carolina, making it one of the largest in the Union Army (though two were detached to join the X Corps in early 1863), and placed under the command of General John G. Foster.

During the spring of 1864, the corps—now commanded by General William Farrar Smith, formerly of VI Corps—was transferred to Yorktown, Virginia, to join Maj. Gen. Benjamin Butler's Army of the James.

The corps played a major part in the unsuccessful operations in the Bermuda Hundred, and was also heavily engaged at Cold Harbor.

On June 12, Lt. Gen. Ulysses S. Grant sent Smith on a surprise march to seize Petersburg from the Confederate forces before Robert E. Lee could bring up the bulk of the Army of Northern Virginia.

Charles A. Heckman briefly commanded the corps following the wounding of General Ord during the Battle of Chaffin's Farm.