The Long Tom Rebellion is sometimes considered the only Civil War battle fought in Oregon -- and it happened after the Civil War had ended.
Philip Henry Mulkey was a pioneer, circuit-riding Baptist preacher who had settled in the Long Tom community west of Eugene, Ore. On May 9, 1865, after learning Lincoln had been assassinated, Mulkey walked the streets of Eugene, shouting, “Hurray for Jeff Davis and damn the man who won’t.” The First Oregon Volunteer Infantry quickly detained and jailed him.
When a pro-Union mob broke into the jail to lynch Mulkey, he brandished a knife and slashed out at his first attacker. The lynch mob fell back just long enough for the soldiers to restore order.
Meanwhile, on Long Tom Creek, Mulkey’s friends and neighbors were gathering to march into town and release him. The soldiers got word of it and quietly moved Mulkey to a steamboat for a trip to the prison at Fort Vancouver. Thus ended Oregon’s Civil War battle.
When Mulkey was released three months later, he sued for false arrest and violation of his First Amendment rights. Two years and 14 court appearances later he settled for $200.
Source: "Oregon History: Civil War in Oregon." Oregon Blue Book, State of Oregon, 2016, bluebook.state.or.us/cultural/history/history16.htm. Accessed 1 Nov. 2016.