Discovered check and windmill: the pin with roles reversed

In short

In a discovered check three pieces stand on one line: your threatening piece, your moving piece and the opponent’s king. In a pin the piece in the middle belongs to the opponent; in a discovered check it belongs to you. Nimzowitsch puts it vividly: the weak, pinned piece has changed sides and become a strong warrior.

The opponent must first get out of check. This often gives the moving piece time to capture material, attack a valuable piece or reach a better square. But check whether the opponent can capture that piece and get out of check at the same time.

A windmill arises when the opponent’s king has only one single move after each discovered check. Your piece then comes back with check and moves away again at once. With each discovery it may choose a different square on its line. In this way it collects one enemy piece after another.

If the moving piece also gives check itself, that is called a double check. Only a legal king move can meet it. The king may capture one of the checking pieces, provided it is not in check afterwards. Nimzowitsch counts the double check among the purely tactical weapons.

Summarized by the editors in their own words. This is not a quotation.

Not every discovered check is the best move

A discovered check often looks strong. Even so, a second look is worthwhile. In the game against Rubinstein, at the end a white rook, a bishop and the black king stand on one line.

Here you expect a quick discovered check. But Nimzowitsch finds something better with a king move and so catches the reader off guard. The discovered check would have achieved less in this position.

For practice

In Lesson 14 you move a piece out of the way yourself and win material in the process. There you will also find a double check from the game Réti – Tartakower, which Nimzowitsch shows in his chapter.

If you do not know the pin yet, start with Lesson 13. By the way, Nimzowitsch made up the two windmill positions in “My System” especially for his book.

Today’s view

Today people also speak of a discovered attack. Here the uncovered piece does not attack the king but, for example, the queen. Then the opponent does not have to respond at once, as with a check. The moving piece therefore has a little less freedom.

With every discovery, check whether the opponent’s king can capture your moving piece. If it stands unprotected next to the king, it is in danger.

Where to find it in Nimzowitsch

• My System: I. Teil, 8. Kapitel - Das Abzugsschach original text not yet published

  Overview of the short chapter on the discovered check, with its three sections.

• My System: I. Teil, 8.1 Der Verwandtschaftsgrad zwischen der „Fesselung“ und dem „Abzugsschach“ wird näher präzisiert. Wohin zieht der aufdeckende Stein am besten? original text not yet published

  The discovered check as a transformed pin, and the three options of the moving piece.

• My System: I. Teil, 8.2 Die Zwickmühle original text not yet published

  The windmill, with two specially composed positions and a finish from Torre – Lasker.

• My System: I. Teil, 8.3 Das Doppelschach original text not yet published

  The double check, against which only a king move helps, with three short game examples.

• Chess Praxis: Partie 83 (original text)

  Nimzowitsch – Rubinstein: at the end you expect a discovered check, but a king move is stronger.

In the course

• A piece that cannot move
• A move opens an attack
• Nimzowitsch – Rubinstein, Semmering 1926