Pawn on the Sixth: Only Ra7+ Holds

Watch the method: press play to see the winning idea run, or step through it move by move.

The pawn on the sixth with the attacking king in front of it sits on a knife edge. With White to move it is won. With Black to move it is drawn, and exactly one move draws.

Only Ra7+. The check kicks the white king off e7 before it can step to e8 and free the pawn. Every other rook move and every king move loses.

Checking distance. A defending rook needs roughly three files between itself and the enemy king, so the king cannot answer a check by walking at the rook. From the a-file against a king on d or e, the checks never end.

A pawn on the sixth shelters nothing. It does not screen its own king from checks along the ranks, which is why the white king gets chased away from the pawn instead of escorting it.

In this drill you must find the holding resource at once. One loose move hands back the tempo and the win returns.