| 8. Q - B 2 | P × P | |
| 9. B × P | Kt - Q 4 | |
| 10. B × B | Q × B | |
| 11. O - O | Kt × Kt | |
| 12. Q × Kt | P - Q Kt 3 |
This is the key to this system of defence. Having simplified the game considerably by a series of exchanges, Black will now develop his Q B along the long diagonal without having created any apparent weakness. The proper development of the Q B is Black's greatest problem in the Queen's Gambit.
| 13. P - K 4 | B - Kt 2 | |
| 14. K R - K 1 | K R - Q 1 |
The developing stage can now be said to be complete on both sides. The opening is over and the middle-game begins. White, as is generally the case, has
obtained the centre. Black, on the other hand, is entrenched in his first three ranks, and if given time will post his Q R at Q B 1 and his Knight at K B 3, and finally play P - Q B 4, in order to break up White's centre and give full action to the Black Bishop posted at Q Kt 2. In this game White attempts to anticipate that plan by initiating an advance on the centre, which, when carefully analysed, is truly an attack against Black's K P.
| 15. P - Q 5 | Kt - B 4 ! |
Against Kostic in a previous game I had played Kt - B 1. It was carelessness on my part, but Marshall believed differently, otherwise he would not have played this variation, since, had he analysed this move, he would, I think, have realised that Black would obtain an excellent game. Black now threatens not only B P × P; but also Kt × P; followed by B P × P. The position is very interesting and full of possibilities.
