Morphy Defense

The Morphy Defense, 3...a6, is Black's standard answer to the Ruy Lopez, or Spanish Game, and occurs in about two-thirds of games that begin with 3. Bb5. The pawn forces White to decide immediately: give up the bishop for the knight or pull it back. The gain for Black is a permanent option of ...b5, which can be used whenever the pin on c6 becomes inconvenient. The cost is a slight loosening of the queenside.

The retreat 4. Ba4 is chosen in roughly three games out of five. It keeps the bishop pair and the indirect pressure on c6. This follows Jaenisch's view that the bishop's real task is to slow Black's queenside development, not to inflict doubled pawns. The Exchange Variation, 4. Bxc6, makes up most of the remaining games, while 4. Bc4 is a rare sideline in which Black scores well. Once the bishop stands on a4, White must watch for the Noah's Ark Trap, in which ...b5 and ...c4 shut the piece in on b3.

After 4. Ba4, Black's usual move is 4...Nf6, the reply Morphy himself preferred. White most often plays 5. O-O and leaves e4 hanging, since the pawn can be won back if Black takes it. Black then has several systems. 5...Be7 leads to the Closed Defense and 5...Nxe4 to the Open. The other choices are 5...Bc5, the Møller Variation, and 5...d6, the Steinitz Deferred. With 5...b5 6. Bb3, Black can choose 6...Bb7, the Arkhangelsk Variation, or 6...Bc5, the Neo-Arkhangelsk. White's fifth-move alternatives include the quiet Anderssen Variation 5. d3, the Tarrasch Variation 5. Nc3 and the Mackenzie Variation 5. d4.

Black can also depart from the main line on move four. 4...d6, the Modern Steinitz Defense, supports e5 as the older Steinitz does, but ...b5 is now on hand to break the pin. 4...Bc5 is the Classical Defense Deferred. 4...b5, the Caro Variation, settles the bishop's fate at once. After 5. Bb3, Black can continue with 5...Na5, the Norwegian Variation, which hunts the bishop, or with 5...Bc5, the Graz Variation.

The move was first recorded by Ercole del Rio in 1750. Charles Henry Stanley played it in his 1845 match with Eugène Rousseau, and Staunton mentioned it in 1847. It took Morphy's name after he adopted it against Anderssen and Löwenthal in 1858, although he did not invent it. Steinitz disapproved in 1889, arguing that the bishop stands better on a4 than on b5, but later practice rejected his verdict. Engines rate the position as roughly balanced, and White scores slightly better in online play.