12. K-B2 K-B5
The White King cannot move to Kt2 now, because in that case Black would move the King to the White QBP and queen in seven moves, and White, after seven moves, would only have the KB pawn at B7.
13. K-K2 K-Kt6 14. K-K3 P-B4
and wins, for White cannot hold the KBP now, but must capture the KtP in exchange for it, after which the Black King reaches the Queen’s side two moves ahead, e.g.:
15. K-K2 K-Kt7 16. K-K3 K-B8! 17. K-K4 K-B7 18. K-B5 KxP 19. KxP K-K6, etc.
Black would have forced a win also if White had played K-Kt2 on his twelfth move thus: 12. K-Kt2, K-B5; 13. K-B2.
Now White has the opposition, and after Black wrings it from him by playing the spare move P-B4, he assumes it again with 14. K- K2, K-Kt6; 15. K-K3. But he cannot maintain it after Black’s K-R6 because the square at Q3 for distant opposition is not accessible. After 16. K-Q2, K-R7!; 17. K-K3, K-Kt6; 18. K-K2, K- Kt7; 19. K-K3, K-B8 we get the same result as before.
II. FROM A GAME ED. LASKER-ROTLEVI (HAMBURG, 1910).
Diag. 83