Go To The Mattresses Meaning

(idiomatic) To go to war; to use ruthless tactics; to act without restraint.

Example: 1969, Mario Puzo, The Godfather, Putnam, p.132:
  I want Sollozzo. If not, it's all-out war. We'll go to the mattresses.
1988, Glen Waggoner, "Sports: Collusion Is Over, but Excess Is Back," New York Times, 18 Dec. (retrieved 21 Sep. 2008):
  They will have to go to the mattresses; that is they will have to risk a long ugly strike.
2008, "Transcript: CNN LARRY KING LIVE—Interview with Senator Hillary Clinton," CNN analyst Jamal Simmons speaking, 21 Apr.:
  Now, when you're fighting Republicans . . . Democrats are all rallied around and ready to go ahead and go to the mattresses.