The ambush at Sand Butte was revenge served with tactical brilliance. Just weeks earlier, on April 11, Modoc leaders Kintpuash (Captain Jack) and others had killed General Edward Canby and Reverend Eleazer Thomas during a peace parley. Canby would become the only U.S. general killed in the entire Indian Wars. The Army responded by authorizing Donald McKay, a mixed-race mercenary who led the Warm Springs Indians, to recruit his tribesmen against the Modoc. When the Army attacked Captain Jack's Stronghold on April 18, they found it nearly abandoned - the Modoc had slipped away the night before. What soldiers discovered there haunted them: elderly and wounded Modoc had been burned. The war had descended into atrocity.

On the morning of April 26, seventy Army soldiers left Gillem's Camp near the Stronghold and marched south toward Sand Butte, four miles away. Captain Evan Thomas and Lieutenant Thomas Wright led the patrol, hoping to position a mortar battery atop the butte. The soldiers spread out in a line, fully visible, making noise. The Modoc watched from concealment, forming a parallel line and following unseen. Around noon, the patrol stopped at the base of Sand Butte to rest and eat lunch. Donald McKay and a dozen Warm Springs scouts joined them. They had walked directly into a trap surrounded by ridges on all sides, with the butte rising 200 feet above them.

Kintpuash and Scarface Charley positioned their twenty to thirty warriors perfectly. One group held trees on Sand Butte's northern face. Two flanking squads covered the north and south. A few more took position on a western ridge. When Captain Thomas sent three soldiers to picket the ridge, the Modoc opened fire before they could be spotted. Back at Gillem's Camp, officers heard the gunfire but assumed their superior numbers guaranteed victory. They were wrong. Soldiers fled in every direction, some so panicked they fired on the Warm Springs scouts coming to help. When survivors stumbled into camp at 1:30 p.m., their reports seemed too terrible to believe.

Colonel Gillem finally ordered a relief force to Sand Butte, but darkness fell before they arrived. The surviving soldiers built low rock walls and prepared to spend the night surrounded by their dead. More survivors reached camp at midnight, and Warm Springs scouts agreed to lead a rescue at dawn. They couldn't navigate the lava beds in darkness. When morning came, the rescue party found the bodies: thirty-six casualties including Captain Thomas and Lieutenant Wright. It was, as one newspaper would call it, a catastrophe.

The American press responded with fury. Harper's Weekly published an illustration titled "Modoc Scalping and Torturing Soldiers." Frank Leslie's Illustrated Newsletter ran a drawing of a Modoc warrior scalping a fallen soldier while a vulture perched nearby, captioned "The Two Vultures." The subtext was clear: the Modoc had forfeited any claim to mercy. The escape from the Stronghold and the massacre at Sand Butte transformed the conflict from a frontier skirmish into a cause celebre demanding extermination. Within weeks, the Modoc band would fracture, betray its leaders, and watch Captain Jack hang at Fort Klamath. The tactical genius displayed at Sand Butte only accelerated their destruction.