Perpetual check or promotion — it must start at once

Draw White to move · Queen endgames · Difficulty about Elo 1800

The plan

The counter-calculation to the previous lesson. Here the black pawn is the faster one: it needs only two more moves to promote, the white one three. It can no longer be stopped, and there is no fortress in this material. Exactly one means remains — perpetual check. Only it is not an emergency exit you can take whenever you like: it has to start on this very move, and with the right check. Of twenty-three possible moves exactly one holds, and one half-move later it is again only one out of twenty-two. The reason is that the check series does not have to run without a break, but it does have to be covered without a gap: between two checks stands a quiet move that holds up the enemy pawn, and only from there do the checks reach again. Then the queen chases the enemy king right across the board, without it ever finding a square where the checks run out.

Rule of thumb: perpetual check is not a stock you can save up — begun one move too late, it is not perpetual check at all any more.

Why this level: Grab the perpetual check at once — one move out of 22 holds

The solution, move by move

1. 1. Qc5+ The ONLY move that holds — twenty-two others lose. The check forces the king onto a file from which the queen immediately reaches the square IN FRONT OF the black pawn. Whoever lets their own pawn run instead loses it with check (first sideline); whoever wants to trade queens loses the pawn endgame (second sideline).
   Sideline 1. f6 Counter-attack with your own pawn — the right idea, one move too late. The black pawn is simply faster. 1… Qf1+ Black checks first and thereby takes the time White has just spent. 2. Kd5 Qf5+ 3. Kd6 Qxf6+ The white pawn falls with check, and with it the last counterweight is gone. 4. Kd7 Qd4+ The white king stands in the open, the queen cannot check forever, and the black pawn promotes at its leisure. Lost.
   Sideline 1. Qe1+ The other reflex: get out of trouble, trade queens and hold the pawn endgame. 1… Qxe1 Except in the pawn endgame all that counts is who is faster. 2. Kd5 Kh2 The black pawn needs two moves to promote, the white one three — and neither king can get in between. Lost. Trading queens is the weapon of the STRONGER side; whoever is behind must keep the queens on the board at all costs. 3. Kd6 Kh3 4. Kd7 Kh4
2. 1… Kh2 Black evades. Four of its five moves hold the draw anyway — here it is the defender who faces the hard task, not the attacker.
3. 2. Qe5 The ONLY move, and a QUIET one too. The queen places itself diagonally in front of the black pawn: it can go no further, and at the same time the queen now stands so that the check series never runs out from here on. Every other move loses, including every further check (third sideline).
   Sideline 2. Qc7 Keep checking instead of making the quiet move? From here the queen even attacks the black king directly — and yet stands wrongly. 2… Qc2+ First an in-between check, 3. Kd5 Qxc7 and then the queen simply falls. That is exactly why the quiet move is needed: it is the only square from which the queen holds up the pawn AND stands safe itself. 4. Ke6 Qd8 5. Kf7
4. 2… Kh3
5. 3. Qh8+ From here it is pure pursuit. The queen takes the long diagonal and the eighth rank in turn.
6. 3… Kg4
7. 4. Qg8+ The king runs upward, the queen follows it on the same rank. Only one thing matters: never offer a square where the black queen could step in between.
8. 4… Kh5
9. 5. Qh8+
10. 5… Kg5
11. 6. Qg8+ Always the same picture, always the same two squares. This is what a clean perpetual check looks like — two stand-by squares for the queen and no progress whatsoever for the opponent.
12. 6… Kf6
13. 7. Qh8+ The black king has meanwhile crossed half the board. Its pawn still stands where it stood: as long as the king has to dodge, it cannot push it.
14. 7… Kf7
15. 8. Qh7+
16. 8… Kf8
17. 9. Qh8+ And the same check again. White has shared the point, even though he was hopelessly behind with the pawn.

More in Queen endgames

• The more advanced pawn — why the trade is the weapon White wins
• Trade first, then promote — the pawn captures forward White wins
• Perpetual check or mate — the king marches behind the queen White wins
• The king looks for cover — behind the enemy pawn White wins
• Queen against rook and bishop — both on a knife's edge Draw
• Queen against two knights — the king step decides White wins