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

White has to move the rook from e5. The safest square for it is back on e1: There's also the sideline which seems to be motivated as much by novelty as anything else - the defence of f2 isn't generally an important factor, and the rook on e2 cuts the White queen's contact with h5 which gives Black the option of retreating her own queen there (from h3, after ...Qh4 g3 Qh3) in some lines.
 * 13. Re1
 * 13. Re2