throw down the gauntlet Definition

gauntlet¹
noun

1. historical
A metal or metal-plated glove worn by medieval soldiers.
2. A heavy protective leather glove loosely covering the wrist.

Idiom: take up the gauntlet

To accept a challenge.

Idiom: throw down the gauntlet

To make a challenge.

Etymology: 15c: from French gantelet, diminutive of gant glove; the idioms are derived from the former practice of throwing a gauntlet on the ground when issuing a challenge to a duel and picking it up when accepting such a challenge.