Will Fight Until the Bitter End?

If you say that you will continue doing something to the bitter end, especially something difficult or unpleasant, you are emphasizing that you will continue doing it until it is completely finished. The guerrillas would fight to the bitter end, he said, in order to achieve their main goal.

What does till the bitter end mean?

Definition of to/until the bitter end

: until the end of something that may be very bad, unpleasant, etc. I knew she would stand by me to the bitter end. He vowed that he would keep fighting until the bitter end.

Which end is the bitter end?

The bitt end (or bitter end) refers to the final part of the anchor rope near to where the rope is fixed to the ship's deck. Usually marked with coloured rags, the bitter end gets its name from the bollards (or bitts) on the deck to which the anchor rope was tied.