the.com/stab in the back

means To betray or attack someone, especially a trusting ally, through a treacherous or secretive act — often used for the lie or smear that wrecks your reputation when you weren't looking.

from Literal and brutal at first — a knife driven into someone's unprotected back rather than their front, where they could see it coming and fight back. The phrase took on its political life especially through the 'stab-in-the-back myth' (Dolchstoßlegende), the poisonous post-WWI German lie that the army hadn't really lost the war but had been betrayed by civilians at home — a textbook case of a metaphor weaponized into propaganda. That history is a stark reminder of how the phrase carries real political weight, but the plain image — treachery from behind, where you can't defend yourself — is older and simpler than any single myth.