Right To The Bitter End

My Grandpa is a retired sea captain and when I ask him the right questions he will tell me stories about his years at sea.  

Today, he told me that the term bitter end originates from a nautical term.  A bitt is a wooden or iron post that is fastened through the ship's deck in order to secure the anchor.  If all of the anchor cable has been released into the water you have come to the bitter end.