The McDonnell Gambit is a chess opening gambit in the King's Gambit, Classical Variation that begins with the moves:[2] or alternatively via the Quaade Gambit:[3][4] The opening is named after Alexander McDonnell, a 19th-century Irish chess master, who successfully introduced it in his third match with Louis-Charles Mahé de La Bourdonnais.

The aim is to gain a significant lead in development (knight, bishop, and queen) for the sacrificed knight, followed by a kingside attack.

The McDonnell Gambit has always been much less popular for White than the similarly motivated Muzio Gambit (4.Bc4 g4 5.0-0).

Although considered obsolete by MCO,[5] it has not been thoroughly tested.

Qxf3 is usual, though the wild 6.0-0 is occasionally seen.

Now 6...Bh6 (as in the McDonnell–La Bourdonnais game below) is regarded as inferior.

Better options for Black are: 1. e4 e5 2. f4 exf4 3.

Nd5 White can try 8.d5!?

Bc8 9.Bxf4 as in Dufresne–Anderssen, Berlin 1851 (Korchnoi).

Black had a clear advantage after 14...Qb6!

15.Qa3 Qxd4 16.Rf2 Be4 17.Bxe7 Nxe7 18.d6 Rg8 19.Rxe4 Qxe4 20.Re2 Qxe2 21.Bxe2 Nc6 in Barth–Lenz, corr.