Treason – Wikipedia

In addition to the Conspiracies Act of July 31, 1861, in 1862, the federal government went further to redefine treason in the context of the civil war. The act that was passed is entitled “An Act to Suppress Insurrection; to punish Treason and Rebellion, to seize and confiscate the Property of Rebels, and for other purposes”.

https://en.wikipedia.org/wiki/Treason