Reproduction of this essay in whole or in part for noncommercial purposes, with attribution and with notice of
copyright, is permitted; reproduction of this essay in whole or in part for commercial purposes, or without attribution,
or without notice of copyright, without the author's express permission, is not permitted.
Chess diagrams appear thanks to Steve Eddins's ChessImager,
available here.
Little Lesson 5: The Queening Square
When a king and an opposing pawn engage in a footrace, the winner is determined by whether or not the king
is inside the queening square of the pawn.
&ds_color=(0,64,255))
In the diagram above, the Black king is inside the queening square of the White pawn, but the White king
is not inside the queening square of the Black pawn. The white pawn's queening square is the box of
squares contained within the boundary h5-h8-e8-e5-h5, including the squares on that boundary (and, therefore,
including the square e6, where the Black king sits). The Black pawn's queening square is the box of
squares contained within the boundary a4-a1-d1-d4-a4, including the squares on that boundary (but not
containing e4, where the White king sits). Black's king, being inside the White pawn's queening square
already, can stop the White pawn from queening no matter which player is on move; however, White's king
can only stop Black's pawn from queening if it is White's move. If it is Black to move, he plays 1 ... a3
and wins. On the other hand, if it is White's move, he plays 1 Kd4 or 1 Kd3, stepping into the Black
pawn's queening square.
The leftmost position is drawn no matter whose move it is. The Black bishop and king will easily stop
the White g-pawn; and if White, on move, plays 1 Nxd6 Kxd6, Black's king is within the pawn's queening
square. On the other hand, while the position in the middle is drawn if it's Black's move--he moves 1 Bd4
or 1 Be3, putting the Black bishop where it can capture the g-pawn before it can queen--the position is a win
for White if it's White's move. After 1 Nxb6 Kxb6 (1 Nxb6 Kd6 2 Nc4+ Ke6 3 Ne3 holds the pawn), Black's
king has been pulled outside the g-pawn's queening square (g4-g8-c8-c4-g4) with White to move. If the
Black king is outside the White pawn's queening square with White to move (so that the Black king can't step
into the queening square), the pawn can march down the board without being caught.
Hence, White to move can win the rightmost position by 1 Bxb6 Bxb6 2 Nxb6 Kxb6, resulting in the middle
position, with the Black king outside the queening square with White to move.
The really important thing, however, is having a path to the queening square that enables the defending
king to reach the queening square in time to stop the advancing pawn. In the leftmost figure above,
Black's king is within the queening square of White's g5-pawn, but that isn't good enough if it is White
to move, because Black's own e6-pawn blocks his king's direct route to g8, slowing it down just enough to
enable White to queen. Similarly, the Black king in the middle diagram (which is diagram 106 in Lev
Alburt's Chess Training Pocket Book: 300 Most Important Positions & Ideas), while able to step
into the f-pawn's queening square, can have his path blocked: 1 d6! cxd6 2 f5, and the White pawn will
queen. (Of course, Black to move draws by playing 1 ... Kc5.) And in the rightmost diagram, White to
play wins by 1 Bxd6+ cxd6 2 f5, and the pawn will queen.
An exception to the rule that a king that can step into a pawn's queening square can stop that pawn occurs
when the pawn is still on its second rank--when it has not yet made its first move. Then, because the
pawn's first move can cover two squares, the rule must be amended, and the relevant queening square is the
same as the one used for a pawn that is on the third rank. Hence, even though it might appear that the
Black king can stop the White pawn in the diagram on the left, because the move 1 ... Kb7 would take the
Black king inside the h2-h8-b8-b2-h2 square, the Black king really can't stop the White pawn: 1 ... Kb7
2 h4 Kc7 3 h5 Kd7 4 h6 Ke7 5 h7 Kf7 6 h8=Q. The diagram on the left is really equivalent to the diagram
on the right, as far as the queening square goes; the queening square the Black king really needs to step
inside is the h3-h8-c8-c3-h3 square. If the Black king were already on b7 and could move 1 ... Kc7, it
would be inside the queening square in either diagram; as it is, it can only move 1 ... Kb7, and that won't
stop either pawn.
(© 2008 by Keith Brian Johnson)
Chess Home
Site Home