Orlando Willcox was born on April 16, 1823, in Detroit, Michigan. He entered the U.S. Military Academy at West Point on July 1, 1843, and graduated with a commission as a 2d Lt of Artillery on July 1, 1847. His first assignment was with the 4th U.S. Artillery, and he served at the close of the Mexican-American War from 1847 to 1848 on garrison duty in Mexico City and Cuernavaca. He served in New Mexico and Massachusetts between 1848 and 1856, and then served in Florida during the Third Seminole War from 1856 to 1857. Lt Willcox resigned his commission on September 10, 1857, and went back to Detroit where he practiced law until receiving an appointment as a Colonel of the 1st Michigan Infantry at the beginning of the U.S. Civil War on May 1, 1861. He was wounded and captured during the First Battle of Bull Run on July 21, 1861, and was released on August 19, 1862, at which time he received a commission as a Brigadier General of Volunteers, retroactive to his date of capture. Gen Willcox commanded the 1st Division of IX Corps from August 1862 until the end of the war, including commanding it during the battles at Sharpsburg, Fredericksburg, Knoxsville, and during the Overland Campaign against Richmond in 1864. After the war, he was mustered out of the Army on January 15, 1866, but returned to duty on July 28, 1866, serving with the 29th U.S. Infantry until March 1869. His next assignment was with the 12th U.S. Infantry at San Francisco, California, from 1869 to 1878, followed by service as commander of the Department of Arizona during the Apache Indian Wars from 1878 to 1882, and then commanded the Department of the Missouri. He retired from the U.S. Army on April 16, 1887. Gen Willcox was awarded the Medal of Honor on March 2, 1895, for service during the First Battle of Bull Run in 1861. Orlando Willcox died on May 10, 1907, and was buried at Arlington National Cemetery. The town of Willcox, Arizona, was named in his honor.

His Medal of Honor Citation reads:

Led repeated charges until wounded and taken prisoner.