Game 137 in Philip W. Sergeant’s Morphy’s Games of Chess (1916), printed pages 201. Commentary from this edition; named earlier annotators remain credited in the notes. Played blindfold in Havana, October 22, 1862. The source identifies the opponent as José Maria (Sicre).

1. 12.g4 A move which conscious superiority justifies in a position like the present. When the opponent’s mistake occurs (as at move 13 here), such a manœuvre becomes excellent.
2. 18…Nf6 There is nothing else to be done.