The following is from the book, Encyclopedia of Indian Wars, by Gregory F. Michno.
18 July, 1856: Gov. Issac I. Stevens of Washington Territory, frustrated at the military's feeble campaigning to remove Indians from settled areas, planned a summer expedition into Walla Walla and Yakima Indian country. In early July, Lt. Col. Benjamin F. Shaw took a force of 400 volunteers and marched into Oregon Territory.
In the Grande Ronde Valley-nestled between the Blue and Wallowa Mountains-the expedition came upon 300 Walla Walla, Cayuse, DesChutes, Palouse, nd Umatilla Indians. Shaw sent a Nez Perce scout to talk to them, but the scout came galloping back, saying he heard one Cayuse order others to shoot him. Without hesitation, Shaw ordered his men to charge.
The volunteers attacked, and the Indians ran for their lives. Some went into the brush and trees on the slopes of the mountains. Others headed for the Grande Ronde River, but the volunteers killed them en masse on the banks. Shaw proudly declared, "We may safely conclude that at least forty of the enemy were slain, and many went off wounded."
Of the volunteers, three were killed and four were wounded. Shaw's men destroyed the village and a large supply of food, tipis, and ammunition, and captured 200 horses. Gov. Stevens declared victory, and the stage was set for Indian surrender, which would take place at a grand council of tribes in the Walla Walla Valley in September.
Another story from Michno about Grande Ronde Prairie on 14 August, 1862:
Capt. George B. Curry took 30 men of Company E, 1sts Oregon Cavalry, from Fort Walla Walla to the Grande Ronde Prairie to investigate Cayuse depredations on settlers, hoping to arrest the leaders of the attacks. He ordered ten men to remain at the Umatilla Reservation and continued on. In the Grande Ronde, the settlers described several instances in which Cayuse chiefs Tenounis and Wainicut-hi-hi threatened to kill them if they didn't leave.
Making a night ride, Curry and his soldiers surrounded Tenounis's lodge and held the chief hostage in his tent. The next morning, intending to take Tenounis to Fort Walla Walla for questioning, Curry sent a boy out for horses. But instead of horses, 15 or more Cayuses showed up at the tent. After arguing with the Indians, Curry ordered his men to tie up Tenounis and Wainicut-hi-hi. Just then the two chiefs sprang up, seizing the arms they had concealed in their blankets. Tenounis leveled his gun, but Curry fired first and struck him in the breast. Wainicut-hi-hi was also killed in the tent. Outside, the warriors fired on the soldiers, who were drawn up in a line in front of the lodge. The soldiers returned fire, killing two Cayuses. The remaining Indians fled into the brush.
We have a version of the 1856 battle from Bill Yenne is his book, Indian Wars.
The end of Washington Territory's Yakima War came in an unlikely place-Oregon. In July 1856, Governor Stevens sent his Washington militia under Lieutenant Colonel Benjamin Shaw across the Columbia in pursuit of the Yakima. He caught up with and defeated them in the Grande Ronde Valley. Shaw's victory here on July 18 led to a formal surrender two months later in eastern Washington.