"A horse! A horse! My kingdom for a horse!" is a quote from which play?

The quote "A horse! A horse! My kingdom for a horse!" is from William Shakespeare's play "King Richard III." This line is spoken by the titular character, King Richard III, during the climactic battle scene in Act 5, Scene 4. Richard utters this famous line in a moment of desperation during the Battle of Bosworth Field, as he finds himself unhorsed and in a perilous situation. The line exemplifies his urgent need for a horse to return to battle effectively, reflecting his extreme desperation. The other plays listed—The Merchant of Venice, The Merry Wives of Windsor, and As You Like It—do not feature this quote.