411 REFERENCE · Wikibooks
Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...Nf6/5. O-O/5...Be7/6. Re1/6...b5
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Closed Spanish C79 Morphy defence → Closed Spanish → 6. Re1
6...b5
Black ends White's pressure on their knight.
7. Bb3 is necessary to save the bishop.
References
See also
Ruy Lopez
fi:Shakkiaapinen/Peli/1. e4/1...e5/2. Rf3/2...Rc6/3. Lb5/3...a6/4. La4/4...Rf6/5. 0-0/5...Le7/6. Te1/6...b5