The ECO code for the Damiano Defence is C40 (King's Knight Opening).

g6 5.Nxg6 Qxe4+ 6.Be2 Qxg6 leaves Black ahead a piece for a pawn)[4] 4...Qxe4+ 5.Be2, Black has regained the pawn but has lost time and weakened their kingside, and will lose more time when White chases the queen with Nc3, or 0-0, Re1, and a move by the bishop on e2.

Nick de Firmian in Modern Chess Openings analyses instead 4...d5 5.d3 dxe4 6.dxe4, when White had a small advantage in Emmanuel Schiffers–Mikhail Chigorin, St. Petersburg 1897.

3.Nxe5, Black could still regain the pawn with 3...Qe7 4.d4 d6, but has not weakened the kingside or prevented the king's knight from developing to f6.

The opening is named after the Portuguese chess author Pedro Damiano (1480–1544), despite the fact that he condemned it as weak and the book may actually be Francesc Vicent’s writing that he signed.

In 1847, Howard Staunton wrote of 2...f6, "This move occurs in the old work of Damiano, who gives some ingenious variations on it.

"[6] Instead, Staunton's contemporary George Walker more logically reserved the term "Damiano Gambit" for the knight sacrifice played by White on the third move: 1.e4 e5 2.Nf3 f6 3.Nxe5.

[7] Staunton referred to [1.e4 e5 2.Nf3] 2...Nc6, a highly respected move then and now, as "Damiano's defence to the K.

Chigorin lost his queen on move 10 (see diagram), but Schiffers played so weakly that Chigorin later missed a brilliant forced mate and only escaped when Schiffers agreed to a draw in a winning position.