5…exd4Worthy of consideration is: 5 ..., B - K Kt 5; 6 P x P, Q x Q ch; 7 K x Q, Castles ch; 8 K - K 2, R - K 1; 9 P - K R 3, B x Kt ch; 10 K x B, P - B 3; with a good game. In this opening Black is justified in assuming the initiative, as the exchange, which has opened a diagonal for his Q B, has furthered his development. If he does not do so, and confines himself to defending tamely, the chances are that he will lose on account of White's majority of pawns on the King's side.
6.Qxd4Compulsory. If B - K 3 instead, 7 B - B 4 attacks Q B 7. B - Q 3 in reply to that would be inferior. By exchanging Bishops White would render the Black Q P 'backward,' and on the open file its capture would be inevitable.
8…Ne7Black prepares to castle on the King's side. It is more usual, and probably stronger, to castle on the Queen's side, as the King then protects the Q B P, which in the present case would be weak if Black's K B were to be exchanged.
10…Re8Black allows his opponent too much latitude on the King's wing. He should prevent White's P - B 5, which obstructs his Q B, by P - K B 4. After P - K 5 the game would be equalised by B - B 4, B x Kt, and B - K 3. A draw would then be practically certain, with the Bishops of opposite colours. Black probably thought White would not risk weakening his K P by P - B 5. But with unfailing judgment Lasker foresees that, in consequence of the greater mobility of his pieces, his attack will be successful before a counter attack on the weak K P can be instituted.
11…f6Even now P - K B 4 was imperative, though it would keep the Bishop from that square. The continuation could have been 12 P - K 5, B - Kt 5; 13 Kt - K 2 (or R 4), Kt - Q 4, and the Bishop is safe.
12.f5This move has a twofold aim. It shuts in the Bishop, and allows B - B 4, exchanging the Black Q B.
12…b6The diagonal Q R 1 - K R 8 is the only one in which the Bishop has any prospects of action. However, as soon as he relinquishes his present diagonal, a White Knight settles at K 6 and the Black Rooks are very much hampered.
13…Bb7Black should have exchanged the Bishops. Now he gets a weak pawn at Q 3. Before playing B - Kt 2, P - B 4 should be played to prevent the Knight getting from Kt 3 - Q 4 - K 6.
19.Rfd2This holds Black's Kt at B 1. White's next move prevents the Bishop getting into action by P - B 4. After depriving all the Black pieces of their mobility, White turns his attention to a determined assault on the Black King.
26…Rae7There are no prospects on the Rook's file, and Black is restricted to keeping his pieces mutually protected. He cannot prevent White from penetrating the King's side.
30.Kf3If Black captures the pawn, he would lose it again forthwith through White's R - R 3, and the pawn at R 3 would also be captured.
33.Kg3The White King leaves the diagonal because Black's P - B 4 would interfere with the combination by which White intends to annihilate Black's game in a few moves.
35.e5A beautiful final stroke.
36.Ne4Threatening mate by R - R 7 ch and Kt x P.
37…Bc8White dares not move the Rook on account of Kt x B and Kt - Q 6 ch.
42.Nc5Mate in two is threatened. Black's only move is Kt - K 2.
Edward Lasker, Chess Strategy (1921) · Public domain · source