A veteran chess player will tell you that an epaulette checkmate of the enemy King is when the King surrounds himself with his own pieces leaving no escape squares available. So any check delivered against such an immobilized Monarch is guaranteed to be a mate. The word Epaulette is a military term describing the ornamental shoulder piece the indicates an officer’s rank.
In the game that follows played at the internet chess club, jjn played the white side against a French Defense and played the variation where he made a federal case out of owning and occupying d4. Black frustrated his plan by never capturing at d4. Many attacking players will castle queenside come hell or highwater especially if their opponent castles kingside.
As you can see in the diagrammed chess position below, White’s Queen at c2 has nowhere to go after Black plays Nb4. The Queen can move so it is not a “pure epaulette Queen mate”, but all exit squares are guarded by Black