To resign in a way to accept responsibility for a mistake. In the era when warriors carried swords and shields, a soldier who was guilty of cowardice or another serious breach of military procedure was expected to do the “honorable thing” by taking his own life. He needed no assistance: he placed his sword's hilt on the ground and, resting the sharpened tip against his bare midsection, fell forward. Although the accepted mode of remorse was a pistol bullet to the brain in the age of firearms, the phrase remained. It is now used metaphorically: a political figure or business executive whose resignation is an expression of regret for a badly made decision will be said to have fallen on his (or her) sword.