November 29, 1847 – Whitman Massacre – The murder of missionaries Dr. Marcus Whitman, Mrs. Narcissa Whitman and twelve others at Walla Walla, Washington by Cayuse and Umatilla Indians, triggering the Cayuse War.
June 17, 1848 – Battle of Coon Creek – When a company of about 140 soldiers were on their way to left join the Santa Fe battalion in Chihuahua, Mexico, they were attacked near the present town of Kinsley, Kansas by some 200 Comanche and Apache Indians.
1848–1855 – Cayuse War – Occurring in Oregon Territory and Washington Territory, the conflict between the Cayuse and white settlers was caused in part by the influx of disease, and resulting in the Whitman Massacre and the Cayuse War.
1849-1863 – Navajo Conflicts – Persistent fighting between the Navajo and the U.S. Army in Arizona and New Mexico led to their expulsion and incarceration on an inhospitable reservation far from their homelands.
Spring, 1850 – Bloody Island Massacre – The murder of up to 200 Pomo people on an island near Upper Lake, California by Nathaniel Lyon and his U. S. Army detachment, in retaliation for the killing of two Clear Lake settlers who had been abusing and murdering Pomo people.
1854-1890 – Sioux Wars – As white settlers moved across the Mississippi River into Minnesota, South Dakota, and Wyoming, the Sioux under Sitting Bull and Crazy Horse resisted to keep their hunting grounds.
August 17, 1854 – Kaibai Creek Massacre – Forty-two Winnemem Wintu men, women and children are killed by white settlers at Kaibai Creek, California.
1855 – Snake River War – Fighting occurred at the junction of the Tucannon River and the Snake River in Washington Territory.
1855 – Klickitat War – This conflict occurred between the Klickitat and Cascade Indians against white settlers along the Columbia River in central Washington. When intimidation and force failed to get the Indians to cede their lands, battles erupted resulting in the Indians being removed from their lands.
1855-1858 – Third Seminole War – Under Chief Billy Bowlegs, the Seminole mounted their final stand against the U.S. in the Florida Everglades. When Bowlegs surrendered; he and others were deported to Indian Territory in Oklahoma.
1855-1856 – Rogue River Wars – In the Rogue River Valley area southern Oregon, conflict between the area Indians and white settlers increased eventually breaking into open warfare.
1855–1858 – Yakima War – A conflict of land rights in Washington state, involving the Nisqually, Muckleshoot, Puyallup, and Klickitat tribes in the state of Washington. The central figure of the war, Nisqually Chief Leschi, was executed.
January-March, 1855 – Klamath and Salmon Indian Wars – Klamath and Salmon River War, aka Klamath War, or Red Cap War, occurred in Klamath County, California after local miners wanted Indians disarmed due to rumors of an uprising. Some of the Native American’s of the Yurok and Karok tribes refused, leading to hostilities resulting in the state militia and U.S. Army involvement. (source)
February, 1856 – Tintic War – A short series of skirmishes occurring in Tintic and Cedar Valleys of Utah, after the conclusion of the Walker War.
1858 – Coeur d’Alene War – Also known as the Spokane-Coeur d’Alene-Paloos War, this second phase of the Yakima War was a series of encounters between the Coeur d’Alenes, Spokanes, Palouses and Northern Paiute tribes and U.S. forces in the Washington and Idaho areas.
September 1, 1858 – Battle of Four Lakes – Also known as the Battle of Spokane Plains, the conflict was part of the Coeur d’Alene War. A force of 600 military men were sent to subdue the tribes, defeating the Indians.
1859 – Mendocino War – A conflict between settlers and Native Americans in California that took place in 1859. Several hundred Indians were killed.
1860 – Paiute War – Also known as Pyramid Lake War, the war was fought between Northern Paiute, along with some Shoshone and Bannock, and white settlers in present-day Nevada. The war culminated in two pitched battles in which approximately 80 whites were killed. Smaller raids and skirmishes continued until a cease-fire was agreed to in August, 1860.
February 26, 1860 – Gunther Island Massacre – Also known as the Humboldt Bay Massacre, local white settlers, without any apparent provocation, attack four Indian villages, slaying 188 Wiyot Indians, mostly women and children in Humboldt County, California.
September 9-10, 1860 – Utter-Van Ornum Massacre – In 1860 one of the worst massacres along the Oregon Trail took place in Idaho. No other Oregon Trail wagon train suffered greater losses than the Utter-Van Ornum wagon train of 1860.
December 18, 1860 – Battle of Pease River – Battle between Comanche Indians under Peta Nocona and a detachment of Texas Rangers, resulting in the slaughter of the Indians, including women, when the Rangers caught the camp totally by surprise.
1860-1865 – California Indian Wars – Numerous battles and skirmishes against Hupa, Wiyot, Yurok, Tolowa, Nomlaki, Chimariko, Tsnungwe, Whilkut, Karuk, Wintun and others.