The Great Hanging at Gainesville was the execution by hanging of 41 suspected Unionists (men loyal to the United States) in Gainesville, Texas, in October 1862 during the American Civil War. Confederate troops shot two additional suspects trying to escape. Confederate troops captured and arrested some 150–200 men in and near Cooke County at a time when numerous North Texas citizens opposed the new law on conscription. Many suspects were tried by a "Citizens' Court" organized by a Confederate military officer. It made up its own rules for conviction and had no status under state law. Although only 11% of county households enslaved people, seven of the 12 men on the jury were enslavers.
The suspects were executed one or two at a time. After several men had been convicted and executed, mob pressure built against the remaining suspects. The jury gave the mob 14 names, and these men were lynched without trial. After being acquitted, another 19 men were returned to court and convicted with no new evidence; they were hanged, all largely because of mob pressure. Most of the victims were Cooke County residents. This is claimed to have been the largest mass hanging in United States history. The Confederate and state courts ended the Citizens Court activities; President Davis dismissed General Paul Octave Hébert as military commander of the state, but Confederate military abuses continued in North Texas.
A privately organized, annual memorialization of the hangings has been held since 2007. The Cooke County Heritage Society planned a formal commemoration in 2012 to mark the 150th anniversary of the Great Hanging. They canceled it when the mayor objected, but a private event brought together descendants of several victims at a family reunion organized with speakers to discuss the event. In 2014, a memorial was erected near the execution site to commemorate the event and its victims.