Janowski–Capablanca, from Havana 1913. Capablanca essays his “Irregular Defence” against the Queen's Pawn — a system meant to keep the centre intact and throw White on his own resources — but a string of inaccuracies hands David Janowski a won endgame. Capablanca annotates the loss frankly in his own public-domain notes from Chess Fundamentals (1921), reproduced below.
9…Bg4At last Black is on his way to obtain full development. The idea of this irregular opening is mainly to throw White on his own resources. At the time the game was played, the system of defence was not as well known as the regular forms of the Queen's Pawn openings. Whether it is sound or not remains yet to be proved. Its good features are that it keeps the centre intact without creating any particular weakness, and that it gives plenty of opportunity for deep and concealed manoeuvring. The drawback is the long time it takes Black to develop his game. It is natural to suppose that White will employ that time to prepare a well-conceived attack, or that he will use the advantage of his development actually to prevent Black's complete development, or failing that, to obtain some definite material advantage.
12…Nxe4A very serious mistake. I considered castling, which was the right move, but desisted because I was afraid that by playing 13 B x Kt, P x B; 14 Kt - Kt 3, B - Kt 3; 15 Kt - B 5, White would obtain a winning position for the end game. Whether right or wrong this shows how closely related are all parts of the game, and consequently how one will influence the other.
14…Bg6Not good. The natural and proper move would have been Kt - K 3, in order to bring all the Black pieces into play. B x Kt at once was also good, as it would have relieved the pressure against Black's King's Pawn, and at the same time have simplified the game. Here it is seen how failure to comply with the elementary logical reasons, that govern any given position, often brings the player into trouble. I was no doubt influenced in my choice of moves by the fear of B - B 5, which was a very threatening move.
19.Rd3P - K R 4, to be followed by P - Kt 4, might have been a more vigorous way to carry on the attack. Black's weak point is unquestionably the Pawn at K 4, which he is compelled to defend with the King. The text move aims at doubling the Rooks, with the ultimate object of placing one of them at Q 6, supported by a Pawn at Q B 5. Black could only stop this by playing P - B 4 which would create a “hole” at Q 5; or by playing P - Kt 3, which would tie the Black Queen to the defence of the Q B P as well as the K P, which she already defends. Black, however, can meet all this by offering the exchange of Rooks, which destroys White's plans. For this reason P - K R 4 appears the proper way to carry on the attack.
20…g5This move is preparatory to P - K Kt 3, which would make Black's position secure. Unfortunately for Black, he did not carry out his original plan.
21…Rxd3P - K Kt 3 would have left Black with a perfectly safe game.
22…Rd8A very serious mistake, which loses a Pawn. P - K Kt 3 was the right move, and would have left Black with a very good game. In fact, if it should come to a simple ending, the position of the Black King would be an advantage.
24.h4This wins a Pawn, as will soon be seen. Black cannot reply 24...Kt - K 3; because 25 P x P ch, Kt x P; 26 Q - R 4 wins the Knight.
36…Nd4The game went on for a few more moves, and, there being no way to counteract the advance of White's two passed Pawns, Black resigned.
José Raúl Capablanca, Chess Fundamentals (1921) · Public domain · source