Chess puzzle (Advantage)
Opening: French_Defense, French_Defense_Classical_Variation
Moves: 1. d4 Nf6 2. Nc3 e6 3. e4 d5 4. e5 Nfd7 5. Nf3 c5 6. Be3 Nc6 7. dxc5 Nxc5 8.
Bb5 Qa5 9. Bxc6+ bxc6 10. O-O Be7 11. a3 O-O *
Position (FEN): r1b2rk1/p3bppp/2p1p3/q1npP3/8/P1N1BN2/1PP2PPP/R2Q1RK1 w - - 1 12
White to move.
Themes:  Middlegame  
Puzzle rating: 860
Best move: b4