Two Queens
Part of the Basic Mates section of Coddy's Endgames journey. Lesson 2 of 26.
Two queens climb the same staircase and climb it fastest of all: one fences, the other checks, and a queen can never be caught at the edge. The danger is the opposite one. Two queens cover so many squares that a quiet move often leaves him no move at all - and that is stalemate, not a win.