William W. McDonald was born around 1842 in Moore County, North Carolina, to John and Jane McDonald. His father was a farmer who owned $300 of real estate by 1850. His father may have died in the 1850s. McDonald grew up and attended school in Moore County, and by the early 1860s, he was working as a farmer.
He enlisted in the Confederate army on March 11, 1862, and he mustered in as a private in Company H of the 46th North Carolina Infantry on April 16. According to his service records, he was 6 feet tall. The regiment took part in the Seven Days’ Battles, the Overland Campaign, and the siege of Petersburg. He fell ill in the summer of 1862, and he spent the next six months recovering.
He was wounded on May 5, 1864, in the Battle of the Wilderness, but he eventually recovered and rejoined the regiment. He deserted in the winter of 1864-65 and fled to Washington, D.C. He swore an oath of allegiance to the Union on February 27, 1865, and federal officials provided transportation to Jacksonville, Florida. He died sometime after February 1865.