Presumably this is considered First Blood???
Per: http://en.wikipedia.org/wiki/Bleeding_Kansas
By November 1855, the (relatively bloodless) "Wakarusa War" between the two sides had begun. In a message to Congress on January 24, 1856, President Franklin Pierce declared the Free-State Topeka government to be a "revolution" against the rightful leaders.
On May 21, 1856, a group of Border Ruffians entered the Free-State stronghold of Lawrence, where they burned the Free State Hotel, destroyed two printing presses, and ransacked homes and stores. The day after, Congressman Preston Brooks from South Carolina physically attacked Senator Charles Sumner of Massachusetts in the Senate chambers, in retaliation for a speech Sumner made that criticized Southerners for proslavery violence in Kansas. These acts in turn inspired John Brown to lead a group of men in Kansas Territory on an attack at a proslavery settlement at Pottawatomie Creek. The group, which included four of Brown's sons, dragged five pro-slavery men from their homes and hacked them to death with broadswords. These actions are regarded by some as the opening salvo of the Civil War.