Save Someone's Bacon Meaning

(idiomatic) To rescue, especially to save someone's life.

Example: 1876, W.H.G. Kingston, The Three Commanders
  [A]n anxious eye had been kept on the pinnace and the vessel she was chasing. "She's up to her," cried Desmond, who was looking through his glass; "she struck without a blow, and there go our fellows tumbling on board. Little doubt, however, about her being a slaver, though, as they must have seen the way in which we got hold of this craft, they thought it as well to save their bacon, and make the best of a bad job."
1896, J.C. Hutcheson, Young Tom Bowling
  [T]he tide being fortunately in our favour, we reached the Saint Vincent in good time, going up the accommodation ladder on the port side, which, as you know, is devoted to the use of the lower deck portion of the crew, just as Eight Bells struck. "Ha, my lads," cried the Jaunty, who stood by the entry-port, "you've just saved your bacon!"
To prevent an undesirable occurrence.
  My lawyer got my first DUI expunged and reversed the second one. As a result, when I got my third DUI, legally I was a first offender, and instead of jail I got probation. That lawyer really saved my bacon.
2010 May 27, "What Steve Ballmer needs to do to save Microsoft's mobile bacon",