fall on one's sword

verb2

1. •
   To resign from a job or other position of responsibility, especially when pressured to do so.

   • [Bob] Stempel was laboring to undo the damage when GM's board forced him to fall on his sword after little more than two years on the job. — 1992
2. •
   To voluntarily take the blame for a situation.

   • The bemedaled Marine refused to fall on his sword and take full blame for the scandal. — 1987