A windmill tactic uses alternating direct checks and discovered checks to move the enemy king back and forth while another piece captures material. It works only when each check forces the king onto the square needed for the next check. The attacker must also know when to stop the cycle and collect the final target.
Use Back and Forward to replay the 15 half-moves from Torre-Lasker, Moscow 1925. The current FEN can be copied at every step. After the lesson, continue from the exact historical position as White against Defender Bot or Beginner Teacher on the full Play Positions board.
Interactive lesson
Replay the Torre-Lasker windmill
White to move: build the checking machine
The rook on g3 already pins the g7-pawn to the king. White must move the bishop onto the f6-h8 diagonal, offer the queen, and create a cycle in which every rook capture also uncovers check.
r3rnk1/pb3pp1/3pp2p/1q4BQ/1P1P4/4N1R1/P4PPP/4R1K1 w - - 4 25Play the historical position
Continue from the starting setup and calculate the game from the board in front of you. Choose a supported opponent and play to the natural result.
What is a windmill tactic in chess?
A windmill, also called a seesaw, is a forcing sequence built from two kinds of check. One piece gives a direct check. When the king moves, that piece moves again and uncovers a check from a long-range partner, usually a bishop. The defender keeps answering checks while the moving piece captures material.
The pattern needs more than a rook and bishop pointing toward a king. The king must have a restricted route, the long-range piece must be safe, and the moving piece must be able to return with check. If one move does not check, the opponent gets time to capture the attacker, save a target, or create a counter-threat.
The Torre-Lasker windmill position
This lesson starts after Emanuel Lasker's 24...Qb5 against Carlos Torre Repetto at Moscow 1925. The public game record gives the result as 1-0. White's rook is on g3, bishop on g5, and queen on h5. Black's king is on g8, with a pawn on g7 and queen on b5.
Starting FEN: r3rnk1/pb3pp1/3pp2p/1q4BQ/1P1P4/4N1R1/P4PPP/4R1K1 w - - 4 25. Chess.js 1.4.0 replayed every move below. Stockfish 17.1 Lite, at one thread, 16 MB hash, full skill, MultiPV 3, and 3,000 ms, evaluated 25.Bf6! at +4.38 for White.
The first move, 25.Bf6!, is the setup. It puts the bishop on the f6-h8 diagonal while the g7-pawn is pinned. The bishop is not protected by the queen: 25...gxf6 is illegal because moving the pawn would expose the king on g8 to the rook on g3. In the game, Black replied 25...Qxh5. That reply is the historical and engine principal line, but it is not Black's only legal move. The forcing windmill begins only after 26.Rxg7+!.
Alternate a direct check with a discovered check
After 26.Rxg7+, the rook gives a direct check and Black has only 26...Kh8. Now the king stands on the bishop's diagonal. White plays 27.Rxf7+. The rook captures a pawn and clears g7, so the bishop on f6 checks the king on h8. That is the discovered check.
Black has only 27...Kg8. White then returns with 28.Rg7+, another direct rook check. After the forced 28...Kh8, 29.Rxb7+ captures the bishop on b7 while uncovering the bishop check again.
The important relationship is not the exact squares b7 and f7. The rook uses the king's forced move as a free tempo. Direct check sends the king onto the diagonal. A rook capture uncovers the bishop. The king returns, and the rook checks again. Each half of the cycle prepares the other half.
Exit the windmill before the checks become empty
A windmill is useful because it reaches an outcome, not because the rook can repeat. After 29...Kg8 30.Rg7+ Kh8, Torre changes direction with 31.Rg5+!. Moving the rook from g7 uncovers the bishop for one last check, while the rook attacks the black queen on h5.
Black has only 31...Kh7. White then plays 32.Rxh5. The queens are gone, and White's rook has also removed the g7-pawn, f7-pawn, and b7-bishop during the checking sequence. The historical game continued, and Torre won.
This is the exit decision. Before repeating a direct check, scan for the best discovered-check square. It should keep the check forcing and attack the most valuable reachable target. The final move of a windmill often stops checking because the accumulated material gain is ready to be collected.
Common windmill mistakes and exceptions
Moving the front piece without check
A rook capture is not free just because a bishop sits behind it. Trace the long-range line after the rook moves. If the bishop does not check the king, the opponent receives a normal turn and may save the target or capture the rook.
Assuming the king must move between two squares
Count every legal king move, capture, block, and capture of the checking piece. In the displayed cycle, Chess.js finds exactly one legal reply to each check from 26.Rxg7+ through 31.Rg5+. A similar position with one extra flight square may break the whole tactic.
Starting the cycle before the anchor is ready
The bishop on g5 is not yet the correct anchor in the starting position. 25.Bf6! changes its diagonal and prevents the pinned g7-pawn from taking it legally. A controlled Stockfish comparison evaluated the quiet 25.a4 at +0.02 after 3,000 ms, while 25.Bf6 reached +4.38. This supports the practical warning that a slow move misses the concrete chance; it does not mean every other move has the same result.
Repeating checks without choosing an exit
Do not collect a low-value target merely because it is available. Look for a square that keeps the discovered check and attacks the queen, rook, mating square, or another decisive target. In Torre-Lasker, 31.Rg5+ is the exit because it checks and attacks the queen on h5.
Expecting every windmill to win material
The same mechanism can lead to mate, repeated checks, or a draw. Evaluate the final position. A windmill name does not guarantee a win, and a historical sequence does not prove that a practice opponent will choose the same line.
Anchor, swing, exit. Secure the long-range anchor so it cannot be removed legally, swing the front piece between direct and discovered checks, then exit with tempo against the best target.
Practise the windmill from the historical position
Replay the lesson until you can label each rook move as a direct check or a discovered check before pressing Forward. Then choose Defender Bot or Beginner Teacher. You play White from the original FEN. Continue from the starting setup and calculate the game from the board in front of you. Choose a supported opponent and play to the natural result.
The read-only lesson verifies the recorded game sequence. The full Play Positions board is open practice and keeps its normal opponent and side controls. It does not promise 25...Qxh5 or any later historical reply.
Review the general tactics guide for discovered attacks, and use the calculation guide to order checks and captures. Compare the rook-and-bishop partnership with the edge cage in Anastasia's Mate. The rook activity guide explains why entry squares matter, and the tactics trainer gives more positions to solve.
How this lesson was checked: Olivers Grants wrote the article, and developer and ML researcher Uldis Briedis reviewed the technical implementation. The PGN Mentor game record and US Chess educational archive verify the historical position and moves. Chess.js 1.4.0 replayed all 15 half-moves and counted the legal replies. Stockfish 17.1 Lite WASM checked the starting position and quiet-move alternative under the recorded limits.