The most important single feature of a chess position is the activity of the pieces. This is absolutely fundamental in all phases of the game.
Michael Stean in Simple Chess
Jakob Rosanes – Adolf Anderssen
Breslau – Breslau -, 1862
1.e4 e5 2.f4 d5
The Falkbeer Counter Gambit.
3.exd5 e4 4.Bb5+ c6 5.dxc6 Nxc6 6.Nc3 Nf6 7.Qe2 Bc5!
Q – Is it good to sacrifice another pawn?
A – Black is offering another pawn in order to complete his development. After 8… 0–0 White will be behind in development and the fact that his queen and king are on the same file which gives Black some attacking chances.
Black is threatening to win a knight.
Q – Was it compulsory to take on c6?
A – Yes, as 9.d3 Nd4 or 9.Bd3 Re8 10.Kf1 Bf5 lose in a straightforward way.
9…bxc6 10.d3 Re8 11.Bd2 Nxe4
11…Bf5 and Ng4 are also winning. Can you work out how for yourself?
12.dxe4 Bf5 13.e5 Qb6
Compare the relative positions of the two armies. White is two pawns up but his army is poorly coordinated and passive. On the other hand all Black’s pieces are active and ready to launch an attack on the opposing king.
More proof that chess masterpieces require the generous cooperation of the loser (Kasparov)! With 14. Nf3 white can prolong the fight.
15.Bc3 is a better option though it is also losing. 15…Bxc3 16.bxc3 Rad8 17.Nf3 Qa5 (with threat of Qxa2) 18.Rxd8 Rxd8 19.Nd4 Qxa2 wins.
16…Qa5 17.Kb2 Bc5 and 16…Bc5 17.Be3 Qa5 18.Rd3 Red8 are also winning.
Now it is checkmate in 5 moves. 17. Kb2 or 17.g4 are also losing, but not immediately.
Opens the b-file.
18.axb3 Rxb3 19.Be1 Be3+
Followed by checkmate on next move after 20.Qxe3 Rb1#. White resigned here.
Do remember this checkmate pattern with rook and bishop.