Shouldering
Shouldering is a king maneuver in which one king steps into a square that cuts the opposing king off from a pawn or from the route toward it, so the opponent cannot approach.
The word comes from the picture of leaning a shoulder into someone to keep him from the ball. Kings can never touch, so the idea is positional: your king steps onto a square beside the path the enemy king needs, covering the squares in front of it, and the opponent has to retreat or take a longer way around.
Shouldering matters most in races. When a passed pawn is running and a king is chasing it, a king that gets in the chaser's way without losing time can win a race that the rule of the square would otherwise award to the chaser. It also helps a king keep an enemy king away from a loose pawn, or away from a key square in front of a pawn.
To spot a chance, trace the route the enemy king wants and ask whether your king can reach a square beside that route in time, ideally with a tempo to spare. Count the steps along diagonals, since a king moves diagonally as quickly as straight. A common mistake is to run directly at the pawn from behind, so the opponent gets the shoulder instead. Another is to aim for a shouldering square next to the enemy king, which is illegal because kings may never stand on adjacent squares.
Also worth reading is Diagonal opposition. Diagonal opposition is the standoff in which the two kings sit on the same diagonal with exactly one empty square between them, so the king that has to move must give ground.
Also worth reading is Reti maneuver. The Reti maneuver is a king walk that heads for two goals at once, usually stopping a distant passed pawn while also supporting the king's own pawn, so the opponent cannot defend against both threats.
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Related terms
The rule of the square is a shortcut for a lone pawn racing an enemy king: draw a square from the pawn's square up to its promotion square, and the king catches the pawn only if it stands inside or can step in.
A passed pawn has a clear road to promotion as far as enemy pawns are concerned: none stands ahead of it on its own file or the two neighboring files, so the opponent must spend a piece or the king to stop it.
Key squares are the target squares for the attacking king in a pawn ending: once it reaches one while its pawn is safe, the pawn promotes by force, no matter whose move it is.
Cutting off the king means placing a rook on a file or rank so that the enemy king cannot cross it, which keeps the king away from the pawns and often makes a rook ending easy to win.
Opposition is a standoff between the two kings on one file or rank with a single empty square between them; whoever does not have to move holds it, because the other king must give up ground.
A pawn promotion race is a position where both sides push passed pawns toward promotion, and the result depends on who queens first and what the new queen can do.
Guides that go further
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