24

Assuming you allow promoted material (since you didn't say anything :-), this (on Page 13 of the PDF) is the (unfortunately, extremely unknown) finite record since ages. It shows the record for the longest sequence of only 1 legal move for each side, with use of promoted material. [Title "Karl Scherer, Feenshach 1980, Page 13"] [FEN "BQ4R1/2Q5/3Q4/4Q1pp/...


18

The best move would have been 16. Rxe5, which entirely eliminates the mate threat, leaving white with a winning advantage. r6r/ppNk1p1p/3p2p1/2p1R3/2P3bq/3Q4/PP3PPP/R1B3K1 b - - 0 16 Here, if black takes the white knight (16. ... Kxc7), 17. Bg5 wins the queen as Qh5 is met with Bd8+.


16

If you don't mind a bushel of promoted Queens, you can get 14 half-moves . . . [Title "14 forced half-moves to checkmate"] [Fen "3b3k/qqqqq3/rr4NK/7R/5N1Q/7Q/B6Q/7R b - - 0 0"] 1... Rxg6+ 2. Nxg6+ Rxg6+ 3. Kxg6+ Qh7+ 4. Rxh7+ Qxh7+ 5. Qxh7+ Qxh7+ 6. Qxh7+ Qxh7+ 7. Qxh7+ Qxh7+ 8. Rxh7#


15

Inspired by Ed Dean's now deleted answer, here is another "infinite loop.” [FEN "8/6p1/1p3pPk/1P3Pp1/1Pp3p1/KpP3P1/1P6/8 - - - 0 0 "]


10

I just remembered a class of chess problem; see item 267 of Tim Krabbé's Open Chess Diary (his whole site is highly recommended): [Title "White mates in 7, Noam Elkies, 2004."] [FEN "KBk5/P1P4p/2Pp3P/P6p/2p3rP/2P3pB/6P1/8 w KQkq - 0 1"] Spoiler: White has some choices here, he can choose different move orders. But it's always checkmate on move 7, no matter ...


10

White to play and mate in 4, while forcing the black king to capture on each move: [fen "1r2qrnk/3R1bRp/pp2nBpp/p3P3/4B3/5PPQ/PPP3N1/1K6 w - - 0 1"] Solution:


9

You mean like this? [FEN "K1k5/P1Pp4/p2P4/Pp6/P1p5/2P5/8/8 - - - 0 0 "] 1. axb5 axb5 a6 b4 cxb4 c3 b5 c2 b6 c1=Q b7# 1-0 White mates in 6. I guess that's 9 consecutive forced moves. It would be eleven except for black's choice of promotion piece on his fifth move. I don't know if it's a record, and I don't know who composed this classic chess problem. ...


8

I'm not aware of any resources documenting the specific situation you're asking about. The closest available is probably this page from Tim Krabbé's chess records which documents the longest known series of mutual checks, but not ending in checkmate. One of the puzzles from the page could end in checkmate via 14.. Qb7# instead of 14...Bxb7+, so this would ...


7

Forcing move is a term for a move that leaves an opponent with a few options, only one of which does not lead to an immediate loss. This could refer to a variety of circumstances. For example, you might see a mate in 3 puzzle in which the first move is a forcing move because the opponent's only other legal move falls to a mate in 1. The term can also be used ...


7

A simpler infinite-loop setting: [FEN "1kb5/1p1p4/1P1P4/8/8/4p1p1/4P1P1/5BK1 w - - 0 1"]


6

Rosie F’s answer is a wonderful one. However, if you want forced in terms of returning a check with a check, and having to make that move by the laws of chess, I have some answers for you. The positions are legal of course. The record with each player having multiple legal moves is 22 ply. [Title "Alexey Khanyan, Tim Krabbe’s Website, 2008"] [FEN &...


6

The question asked in the title is different from the question asked in the body. If it is required that every best option is check, but it is allowed for the players to have non-checking alternatives, then I offer the following. Every best option for White, i.e. every White move which enables White to mate in time against any Black defence (not just checks)...


6

The current record for most forced checkmates in a legal position with no promoted pieces is 29: [Title "Harold Holgate Cross, The Problemist FCS Apr 1936, 2251"] [StartFlipped "0"] [fen "8/1b6/p1N5/P1r5/P3KPr1/QBk1NRP1/P2R1P2/4B3 w KQkq - 0 1"] PDB has it at id P1178654. White is to move. (For the record where the position must be legal and may have ...


5

What prevents 2. Qe2, which would save the White Queen? White's problem is the mating threats from the bishop battery and queen after Qc3. For instance: [Title "lichess puzzle 61506"] [FEN "rn2k3/1b1p1p1N/4pBrb/qp2P3/3P3P/pP1Q4/P4PP1/R2K1B1R b q - 2 19"] 1... Be4 2. Qe2 Qc3 3. Rb1 Qxd4+ 4. Ke1 Qc3+ 5. Kd1 Bxb1 6. Bg5 Rxg5 7. hxg5 Bxh7 and White is lots ...


5

15.g3 looks winning! 16.f4 is coming to win the Bishop on e5.


4

Well, if the player can force stalemate, then he isn't lost. So the strict answer is no :-) There are many elementary endgames where a successful defence is possible only because of stalemate, like king + pawn vs pawn: [FEN "8/3k4/8/2KP4/8/8/8/8 b KQkq - 0 1"] 1...Kc7! 2.d6+ Kd7 3.Kd5 Kd8 4.Kc6 Kc8 5.d7+ Kd8 Kd6 = or king + queen vs king + pawn with the ...


4

White could play 15. Bf4, covering h2 and attacking the Bishop on e5 which can't move due the pin in the e-file. But the probably stronger continuation is 15. g3 followed by 16. f4, winning the bishop on e5 and winning the game...


4

The answer to this has already been given as an answer in a related question. That answer was 55. [Title "Ludwig Zagler, Feenschach 1972"] [FEN "1rB1Q1Q1/1PRQ3Q/2b2k2/2pQ1N1Q/4KRPp/5N2/1R6/B3nn1b w - - 0 1"] The position is taken from Tim Krabbe's website. According to Krabbe: There are 12 mates by Rb2; 1 by g5; 1 by Qd5; 7 by d7; 7 by Qe8, 7 by Qg8; ...


3

I found two cases of 55 forced mates with promoted pieces in Tim Krabbe’s Diary Entry 383. [Title "Ludwig Zagler Feenschach 1972"] [Site "https://timkr.home.xs4all.nl/chess2/diary_17.htm"] [Date "2019.04.17"] [Round "-"] [White "?"] [Black "?"] [Result "*"] [SetUp "1"] [FEN "...


3

I discovered a game from a few weeks ago features a forced mate in 13 moves that was actually played out on the board. The game in question is Dubov-Svane, and the claim for the mate in 13 comes from Agadmator’s analysis video of the game. Testing the given position with the chess.com engine yields a mate in 13, so Agadmator is correct. But Black made a ...


3

9 moves In the linked thread (not quite a duplicate), a valid answer is posed to this question: You mean like this? [FEN "K1k5/P1Pp4/p2P4/Pp6/P1p5/2P5/8/8 - - - 0 0 "] 1. axb5 axb5 a6 b4 cxb4 c3 b5 c2 b6 c1=Q b7# 1-0 White mates in 6. I guess that's 9 consecutive forced moves. It would be eleven except for black's choice of promotion piece on ...


3

There are many beautiful sacrificial games out there and if you look at composed position you will find even more sacrificial combinations leading to mate. This is one of the most famous games, Anderssen-Kieseritsky from 1851, called "The immortal game": rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 1.e4 e5 2.f4 exf4 3.Bc4 Qh4+ 4.Kf1 b5 5.Bxb5 ...


2

Alekhine - Yates http://www.chessgames.com/perl/chessgame?gid=1012179 19 moves. Alekhine resigned a couple of moves before mate.


2

Yes, and it is not even a particularly rare occurrence. Whenever you notice (in a bad position) that there are hardly any legal moves left to you, you can try to find a way to sacrifice your last mobile pieces. A frequent motive is the "untouchable rook", where the last mobile piece, a rook, keeps checking the enemy king. And if it is taken, the result is ...


2

This answer is only the longest forced checkmate, because I missed your condition that each half move be the only legal move for both sides. The following is a forced checkmate in 262 moves (if both sides play perfectly). [fen "6k1/5n2/8/8/8/5n2/1RK5/1N6 w - - 0 1"] 1. Kd3 N3g5 2. Kd4 Ne6+ 3. Kd5 Nc7+ 4. Kc6 Ne6 5. Kd7 Nfg5 6. Kd6 Kg7 7. Ke5 Nc5 8. Kf5 ...


2

I have discovered a case of 16 ply for a sequence of only one legal moves that results in checkmate! It can be found here in a PDF of Feenschach, the 1980 edition. Enjoy! [Title "Bernd Schwarzkopf nach Karl Scherer (Urdruck), Mate In 8"] [FEN "1KN4r/QRRRRRRr/kq6/p1q1R3/PP1q1b2/4q3/5q2/1r4q1 b KQkq - 0 1"] 1... Qxa7+ 2. Rxa7+ Qxa7+ 3. Rxa7+ Qxa7+ 4. Rxa7+ ...


2

The other "motivation" is that it is simply the best move per the computer, that is if a computer can have a "motivation", per se. That is a problem with tactics problems on Lichess, Chess.com, and ChessBase.com...they often do not take into consideration the best human response, which may be harder for the human to see to the end, but the eval is not as ...


1

15.g3 followed by 16.f4 wins for White since the e5-bishop is pinned.


1

Here's a game from 1912 between Edward Lasker and George Alan Thomas. All blacks moves are forced. [fen "rn3rk1/pbppq1pp/1p2pb2/4N2Q/3PN3/3B4/PPP2PPP/R3K2R w KQ - 20 11"] 1... Qxh7+ Kxh7 Nxf6+ Kh6 Neg4+ Kg5 h4+ Kf4 g3+ Kf3 Be2+ Kg2 Rh2+ Kg1 Kd2# 1-0 In answer to your question, I'm sure there's an even better hypothetical board position, but this was a ...


Only top voted, non community-wiki answers of a minimum length are eligible