The Wham Paymaster robbery ( WHAHM) was an armed robbery of a United States Army paymaster and his escort on May 11, 1889, in the Arizona Territory. Major Joseph W. Wham was transporting a payroll consisting of more than US$28,000 in gold and silver coins from Fort Grant to Fort Thomas when he and his escort of eleven Buffalo Soldiers were ambushed. During the attack, the bandits wounded eight of the soldiers, forced them to retreat to cover and stole the payroll.

As a result of their actions under fire, Sergeant Benjamin Brown and Corporal Isaiah Mays were awarded the Medal of Honor while eight other soldiers received a Certificate of Merit. Eleven men, most from the nearby Mormon community of Pima, were arrested, with eight of them ultimately tried on charges of robbery. All of the accused were found not guilty, and the stolen money has never been recovered.