Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...Nf6/5. O-O/5...Be7/6. Re1/6...b5/7. Bb3/7...O-O/8. c3/8...d5/9. exd5/9...Nxd5/10. Nxe5/10...Nxe5/11. Rxe5

Black's knight must be saved from the combined attack by White's bishop and rook.

When the American master Frank Marshall surprised future World Champion Jose Capablanca with the Marshall Gambit in 1918, his chosen follow-up was 11...Nf6, returning the knight to the kingside where Black's attack will be taking place.

But in the century since then, trial and error has caused 11...c6 to evolve into the main line.