411 REFERENCE · Wikibooks
Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...b5/5. Bb3/5...Na5/6. Bxf7
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Ruy Lopez Opening: Morphy Defense, Caro, Norwegian, Nightingale Gambit rd bd qd kd bd nd rd pd pd bl pd pd pd nd pd pd pl nl pl pl pl pl pl pl pl rl nl bl ql kl rl Ruy Lopez
6. Bxf7+!
As we can see here, White played the unexpected move 6. Bxf7+!, sacrificing the Bishop to abuse the position of Black after 6...Kxf7 7. Nxe5 7...Kf6 8.Qh5 8...c6 9.Qf7+! & White has a huge advantage. This is known as the Nightingale Gambit. This is by far the most aggressive & sharp move after 5...Na5.