Sagebrush has it right on the money.
Buckey O'Neill was an Arizona lawyer, miner, cowboy, gambler, newspaperman, sheriff, and congressman. He was also one of the most important members of Teddy Roosevelt's Rough Riders during the Spanish-American War, having recruited many of the volunteers and supervised their training while in San Antonio waiting to be deployed.
Just prior to the famous charge up Kettle (not San Juan) Hill, O'Neill was standing up, smoking a cigarette, and joking with his troops while under withering fire from the ridge. One of his sergeants shouted to him above the noise, "Captain, a bullet is sure to hit you!" to which O'Neill shouted back his reply. O'Neill then calmly turned to another officer. As he started to speak, a bullet struck him in the mouth. Private Tuttle, who was standing nearby, later recalled, "I heard the bullet. You usually can if you're close enough, you know. It makes a sort of 'spat.' He was dead before he hit the ground."