411 REFERENCE · Wikibooks
Chess Opening Theory/1. e4/1...e5/2. Bb5/2...c6/3. Ba4
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Portuguese Opening
3. Ba4
White has retreated the bishop to a safe square, which is still not very effective. Black can now play 3...b5 to attack the bishop again.
1.e4 e5 2.Bb5 c6 3.Ba4