Where the Side Checks Run Out

The defender's best weapon against a pawn on the seventh is a stream of checks from the side. The rule of thumb is that the rook needs a checking distance of at least three files. This position is where that rule stops working.

Rf1+ is the first move, not the rook lift. The check is a free tempo and it pushes the black king away from the action. Two moves here lose outright (Ra1 and Re2) and two more merely draw (Re6 and Re8), so the margin is thin.

Rd1 frees the king. With the rook behind its own pawn, d7 is defended and White's king is no longer chained to d8.

Then walk at the checks. Kc7, and if Ra7+ then Kb6 attacks the checking rook. Ra8, d8=Q, and the rook must give itself up for the new queen.

Three files is the boundary, not the guarantee. Our position "Pawn on the Seventh: Building the Bridge" shows the attacker's standard method. This one shows what happens when the defender's checking distance is only just enough on paper and not on the board.