411 REFERENCE · Wikibooks
Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...Nf6/5. d3/5...b5/6. Bb3
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Ruy Lopez: Anderssen Variation rd bd qd kd bd rd pd pd pd pd pd pd nd nd pd pd pl bl pl nl pl pl pl pl pl pl rl nl bl ql kl rl Ruy Lopez: Morphy Defence
6. Bb3
This retreats the bishop to the only good square. It puts it on a good square where it controls the a2-g8 diagonal.
Ruy Lopez, Morphy Defence