Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...b5

Caro variation Morphy defence 4...b5 · Caro variation Black drives White's bishop away. Black ends White's pressure on their knight, therefore ends the possibility of Bxc6 and makes their e5 pawn more secure. While ...b5 is a common move in Ruy Lopez at some point, it is unusual to play it immediately on move four, because Black's e5 pawn was still defended tactically (Bxc6 dxc6 Nxe5 Qd4! forks White's knight and e4 pawn). 5. Bb3 is the only move. White preserves their bishop and gets the free tempo to move it onto the dangerous a2-g8 long diagonal, eying Black's vulnerable f7 pawn. History 4...b5 made early appearances in the mid-19th century. Charles Henry Stanley (1819―1901) played it with Black against Eugène Rousseau (1805―1870) in New Orleans in 1845, with the continuation 5. Bb3 Nf6.Eugene Rosseau vs Charles Stanley, 1845. Chessgames.com The Graz variation, with 5. Bb3 Bc5, was also common, as played against Morphy in an 1859 consultation game.Paul Morphy vs Allies, 1859. Chessgames.com 4...b5 is named after Horatio Caro (1862―1920), the British-German chess master known for the Caro-Kann defence, who played it from the 1880s. He introduced the continuation 5. Bb3 Bb7 and would play by fianchettoing both bishops.Gustave Simonson vs Horatio Caro, 1887. Chessgames.comJackson Showalter vs Horatio Caro, 1898. Chessgames.comGeza Maroczy vs Horatio Caro, 1898. Chessgames.com The modern mainline continuation, 5. Bb3 Na5, was played by the likes of Mark Taimanov and others,e.g. Boris Spassky vs Mark Taimanov, 1955. Chessgames.com but received the Norwegian soubriquet for Svein Johannessen (1937―2007), a Norwegian IM who adopted the line.e.g. Bobby Fischer vs Svein Johannessen, 1966. Chessgames.com Theory table 5. Bb3 Nf6 6. d4 d6 7. c3 Be7 8. O-O O-O 9. h3 Bb7 10. Re1 Re8 Caro variation + 5. ... Na5 6. O-O d6 7. d4 exd4 8. Nxd4 Bb7 9. Bd2 Nxb3 10. Nxb3 Nf6 + Norwegian variation 5. ... Bc5 6. c3 d6 7. d4 exd4 8. cxd4 Bb6 9. h3 h6 10. O-O Nf6 Graz variation + 5. ... Bb7 6. O-O Nf6 7. - Archangelsk variation(by transposition) 5. ... g6 6. d4 exd4 7. Nxd4 Na5 Mamedyarov line References See also Ruy Lopez