General E.R.S. Canby was a previously decorated Civil War general and was commanding the Pacific Northwest post when he was ordered by President Grant to deal with the messy situation between the Modoc Indians, who wanted their own territory to call home along Lost River, CA and the U.S. Government, who were trying to convince the Modoc tribes (and neighboring Klamath tribes) to relocate to an Indian Reservation in Fort Klamath, OR.
Months of skirmishes between the Modocs and the U.S. Army, along with failed peace talks, led General Canby to head up one final Peace Commission in order to discuss terms with the leader of the warring Modocs, Captain Jack, and his many followers. Unfortunately, for General Canby and a fellow negotiator, Reverend Eleazar Thomas, both were killed by Captain Jack and his men in an attack on the Peace Commission, and the result of this attack led to a long and grueling war at Captain Jack's Stronghold.
The following text comes from a roadside marker near Canby's Cross that describes the events leading up to General Canby's untimely death:
By April 1873, months of peace talks to end the Modoc War had gone nowhere. General E.R.S. Canby found himself caught between President Grant's Indian Peace Policy and the desire of some settlers to have the Army eliminate the Modoc band. The Modoc leader, Captain Jack, was also caught between peace and war factions. Some Modoc argued that-as in their own tradition-once the leaders of an army were killed, the soldiers would retreat. They pressured Captain Jack to act.
Within minutes of a similar attack at Hospital Rock, eight Modoc attacked the commissioners with hidden weapons. When it was over, General Canby and Reverand Eleazer Thomas were dead, and Indian Agent Alfred Meacham lay seriously wounded. The Peace Policy came to an end.
There's an online brochure from the National Parks Service that gives specifics on the Modoc War that you can read. Wikipedia also gives a good writeup on the life of Edward Canby. There is also another marker next to Canby's Cross that poignantly describes the emotions and fallout from the Modoc War and reads:
Canby Cross ~ Over the years, various individuals and groups have made efforts to memorialize the death of General E.R.S. Canby, the only general to be killed in an Indian War. This wooden cross is a replica of an original erected by a U.S. soldier in 1882, just nine years after the event. Some of the very same troops Canby had commended here in the lava beds were still fighting other Indian Wars, and public interest and emotion about such conflicts ran high.
Although the inscription on the cross may elicit strong emotions in some modern visitors, it illuminates the point that people see events through the lens of their own culture and time. In 1873, what some Modocs considered a justifiable war tactic, the U.S. Army considered murder. No monument commemorates the places where Modocs may have felt their attempts to live peaceably were betrayed.
More than any other Modoc War site, Canby Cross represents the vast gulf between the perceptions of the two sides during wartime, and challenges us to look beyond history to the assumptions of our own cultures. As in all wars, there were no innocent parties in this conflict.