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Double Check: The Most Powerful Move

A Double Check occurs when a King is attacked by two different pieces at the same time. This is often achieved by moving a piece that gives check, which simultaneously opens a line for another piece to give check (a discovered check).

Nimzowitsch famously called the double check "the most powerful move in chess" because the opponent must move the King. They cannot block both checks, nor can they capture both checking pieces at once.