Rama: This is a titanic struggle.
With 6. cxd5 exd5, black has solved the problem of the QB, characteristic of the QGD. 8. ... Ne4, is very canny and serves to restrict the whole white army.
12. ... Rf6 initiates a K-side attack which gets serious with 16. ... Qh5. It is very dangerous for white to take the knight with 18. fxe4 fxe4, as this increases the pressure on h3 and leads to a breakthrough.
Not taking didn't really help, though, since after 18. Ne2 f4!, there is h3 again. This forces the blocking move 19. g4 ..., but the sack 19. ... Nxg4, breaks through anyway.
The counter-sack 21. Nxf4 gxf4, leads to the critical position. White's 22. Bxe4 loses the queen directly but is there anything better?
After 27. Bxc2 ..., we reach an ending with B+R+R vs Q+R which is won for black with his pawn-plus. However there are quite a few obstacles still to be overcome.
With 34. Rxc6+ bxc6, 35. Rxd8 Qxf4, black finally has stabilized the situation and can go about winning!
With the brilliant 48. ... Qd3!, black shuts out the white rook with a queen offer that cannot be accepted. After 54. ... Qb3+, 55. Kb1 ..., there is no defense against c3, so white resigns.
In 1930 Bogo was in-between WC matches, while Ahues was German champ. There was a lot of great chess played at San Remo that year.
sac: 19...Nxg4