William Wallace Hensley (listed in some records as William Worley Hensley), son of Samuel C. and Nancy Lovell Hensley, was born in Marion County, Illinois on May 8, 1834. In 1854 he married Rachel Wilson, who died the following year. In 1856, Hensley moved to Macoupin County, Illinois, where he married Nancy A. Biggerstaff (1835-1916); the couple would have 10 children. Soon after, the family moved to Piatt County, Illinois, where William Hensley purchased from the Illinois Central Railroad Company 160 acres of land, which he farmed.

During the American Civil War, Hensley enlisted in Company C of the 21st Illinois Infantry on June 14, 1861. Initially a corporal in the regiment's color guard, Hensley had been promoted to sergeant by 1863. Captured at the Battle of Chickamauga, Hensley was confined at Richmond, Virginia. On November 1, 1863, he was moved to Danville, Virginia, then arrived at Andersonville Prison on April 21, 1864. Around September 1, 1864, Hensley was among 10,000 prisoners moved from Andersonville to Charleston, South Carolina, then to Florence Stockade the following month. In February 1865, Hensley escaped with a small group of fellow prisoners but was recaptured near Georgetown and returned to Florence Stockade. A short time later, he was exchanged at Wilmington, North Carolina. Having become ill in the interim, he was sent to St. John's College Hospital in Annapolis, Maryland, where he spent several months convalescing before returning to Illinois in July 1865. Upon his return, Hensley resumed farming but later worked in real estate and insurance. William Hensley died in Howard, Kansas on June 22, 1914.

The Seventh Congressional District (Illinois) Regiment, Captain Ulysses S. Grant commanding, was mustered into 30 days' state service at Mattoon, Illinois on May 15, 1861. Composed of soldiers from counties in eastern central Illinois, the regiment was mustered into three years' Federal service as the 21st Illinois Infantry on June 28. (Grant, now a colonel, remained commander of the regiment until August 7, when promoted to brigadier general.) The regiment was soon dispatched to Missouri, where it guarded the Hannibal and St. Joseph Railroad line for two weeks. The 21st generally remained in Ironton, Missouri through the fall and winter, though it participated in a battle at Fredericktown on October 21. In January 1862, the regiment marched to Greenville, where it remained until March, when it was organized with other regiments into the Division of Southeast Missouri and began moving into Arkansas. For the next several months, the regiment marched through eastern Arkansas and Missouri, northwest Mississippi, western Tennessee and into Kentucky. On October 8, 1862 the 21st participated in the battle of Perryville. It saw heavy combat at the Battle of Stones River in late December and early January and remained near Mufreesboro until June 1863. Following the Battle of Chickamauga (September 1863), at which the regiment sustained heavy losses, the 21st participated in the siege of Chattanooga, then wintered at Bridgeport, Alabama and Ooltewah, Tennessee. Its three years' service expired, the regiment reenlisted and was granted a month's furlough. It rejoined the service at Kenesaw Mountain, Georgia, then participated in the Atlanta Campaign. For the next several months, the regiment served in Alabama and Tennessee, participating in a number of battles. In June, 1865, the regiment was moved to Texas via New Orleans and was mustered out of service at San Antonio on December 16, 1865.