Shortly after the Walla Walla council in 1855, in which Yakama leaders warned the United States against further settlement of the area, Qualchan and five others killed six settlers on the Yakima River. On September 23, U.S. Indian Agent Andrew Bolon was murdered by a band of Yakama while traveling along The Dalles to discuss the incident with Kamiakin. Qualchan was accused of leading the group which attacked him, although historians such as A.J. Splawn insist Bolon's murder was carried out by Me-cheil, also a nephew of Kamiakin.
Becoming a wanted fugitive by U.S. authorities, he and his father Owhi participated in guerrilla warfare against the US Army for over three years. Qualchan would frequently attack prospectors, miners and others, selling their supplies to The Dalles and other settlements in exchange for weapons and calicos. During one skirmish in mid-March 1856, he and Chief Leschi led an attack against Connell's Prairie but were driven back by militiamen under Gilmore Hays.
"Kamiakin and Qualchan, cannot longer be permitted to remain at large or in the country, they must be surrendered or driven away, and no accommodation should be made with any who will harbor them; let all know that asylum given to either of these troublesome Indians, will be considered in future as evidence of a hostile intention on the part of the tribe".
Following the Horse Camp Slaughter and encouragement from Spokane runners, Owhi visited Colonel George Wright at his camp on Latah Creek intending to negotiate peace. During the meeting he was seized and put in irons. Wright told him that if his son didn't surrender within four days, Owhi was to be hanged. Despite Wright stating his intention to send Qualchan a message demanding he come to the camp, Native witnesses deny one was ever sent.
Qualchan regardless appeared at the tent of Wright soon enough, accompanied by his wife Whist-alks and brother Lo-Kout. It has been speculated that Qualchan may have been unaware that his father had been taken prisoner and instead had been sent by Kamiakin to determine from Wright the treatment the Yakama would receive if they surrendered. Some say he was captured in a brief gun battle while his wife and brother managed to escape. Qualchan's sister Mary Moses said Lo-kout and Qualchan's wife were captured, but released when the Spokane Indians assured the soldiers that they were no relation of Qualchan. The only record of the meeting exists in a report made by Colonel Wright who wrote "Qualchan came to see me at 9 o'clock, at 9:15 he was hung". Later records claim Qualchan cursed Kamiakin before being killed, though this was disputed by his family members alive at the time. His body was made nude after the garments were taken by the executors, who put the corpse partially covered in a shoal. His father was shot several days later attempting to escape from the camp, his saddle given to later Surgeon General Joseph Barnes.
- Qualchan had two younger brothers, Lo-kout (Quo-to-we-not) and Les-high-hite (Pe-noh), and several sisters: Wah-yah-kon, Quo-mollah, Sah-mah-yas, Si-en-wat, San-clow (Mary Moses) and Yam-kumkt. Chief Moses married Quo-mollah and, after Quo-mollah's death, San-clow; the latter (who died in 1939) gave an account of these things in Mary Moses's Statement.
- According to the United States Geological Survey, Latah Creek is officially named Hangman Creek as a result of Qualchan's execution.
- A Seattle, WA experimental musician is named after him.
- A popular golf course was built in the area where he was hanged, and named in his honor.
- Qualchan is featured in a short story by author Sherman Alexie.
- Splawn, A.J. Ka-mi-akin, last hero of the Yakimas, Portland, Or. : Kilham Stationery & Printing Co., 1917 (OCLC 1086645) p. 42
- Ruby, Robert H. and John Arthur Brown. Indians of the Pacific Northwest: A History. Norman: University of Oklahoma Press, 1981. (pg. 140-141) ISBN 0-8061-2113-0
- Lang, William L. Confederacy of Ambition: William Winlock Miller and the Making of Washington Territory. Seattle: University of Washington Press, 1996. (pg. 95) ISBN 0-295-97502-4
- United States Congress. The Executive Documents Printed by the Order of the House of Representatives During the Second Session of the Thirty-Fifth Congress, 1858-59. Washington: James P. Stedman, 1859. (pg. 365)
- Kip, Lawrence. Army life on the Pacific. Redfield, NY: Edward O. Jenkins. 1859. p. 101
- Mary Moses's Statement, p. 15-16
- T. F. Rodenbough. Journal of the Military Service Institution of the United States, vol. 42.
- Potucek, Martin. Idaho's Historic Trails: From Lewis & Clark to Railroads. Caldwell, Indiana: Caxton Press, 2003. (pg. 69-70) ISBN 0-87004-432-X
- Hein, Teri. Atomic Farmgirl: Growing Up Right in the Wrong Place. New York: Houghton Mifflin Books, 2003. (pg. 32-33) ISBN 0-618-30241-7
- Potomac Corral of the Westerners. Great Western Indian Fights. Lincoln: University of Nebraska, 1966. (pg. 70) ISBN 0-8032-5186-6
- Winthrop, Theodore. The Canoe and the Saddle: A Critical Edition. Lincoln: University of Nebraska Press, 2006. (pg. 215) ISBN 0-8032-9863-3
- Various. Mary Moses's Statement. Fairfeild, WA: Ye Galleon Press. 1988, ISBN 0-87770-453-8
- "Hangman (Latah) Creek". Geographic Names Information System, U.S. Geological Survey. Retrieved 2011-11-27.