 Complete the following phrase:  A number of wars occurred in the wake of the Oregon Treaty of 1846 and the creation of Oregon Territory and Washington Territory. Among the causes of conflict were a sudden immigration to the region and a series of gold rushes throughout the Pacific Northwest. The Whitman massacre of 1847 triggered the Cayuse War, which led to fighting from the Cascade Range to the Rocky Mountains. The Cayuse were defeated in 1855, but the conflict had expanded and continued in what became known as the Yakima War 18551858. Washington Territory Governor Isaac Stevens tried to compel Indian tribes to sign treaties ceding land and establishing reservations. The Yakama signed one of the treaties negotiated during the 