throw down the gauntlet; lay down the gauntlet; fling down the gauntlet
If you throw down the gauntlet, you do or say something that challenges someone to take action or to compete against you.
Note: Gauntlets are long thick gloves which protect your hands, wrists, and forearms.
Note: In medieval times, a knight would throw one of his gauntlets (= long gloves) to the ground as a challenge to another knight to fight. If the second knight picked it up, he accepted the challenge.
The largest teaching union yesterday threw down the gauntlet to the Government, threatening strikes if their demands are not met.
He has laid down the gauntlet and presented us with two options which appear to be non-negotiable.
He furiously laid down gauntlet to his attacker over second jobs : “You’ve picked on the wrong people!”