"We was drunk," Joad said softly. "Drunk at a dance. I don’ know how she started. An’ then I felt that knife go in me, an’ that sobered me up. Fust thing I see is Herb comin’ for me again with his knife. They was this here shovel leanin’ against the school house, so I grabbed it an’ smacked ‘im over the head. I never had nothing against Herb. He was a nice fella."
– John Steinbeck
The Grapes of Wrath, Chapter 6. Tom Joad tells Muley Graves about the fight that got him a prison sentence for manslaughter. He says that he killed in self-defense.