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. Rxe5/11...c6/12. d4/12...Bd6/13. Re1/13...Qh4

White has to do something about the double attack on h2. 14.h3 Bxh3! is a disaster, so it has to be 14. g3, one of the key moves of the Marshall Gambit proper.