About this opening
King's Gambit Accepted: Kieseritzky, Polerio Defense is an opening in the Encyclopedia of Chess Openings,
classified under code C39. ECO group C (C00–C99)
covers open games (1.e4 e5) and the French Defence, including the Ruy Lopez, Italian, Scotch and King's Gambit. This particular variation is reached
after 10 half-moves from the
starting position, with the move sequence 1. e4 e5 2. f4 exf4 3. Nf3 g5 4. h4 g4 5. Ne5 Be7.
It belongs to the King's Gambit Accepted family. Within that family this is a level-2 branch (the Kieseritzky → Polerio Defense line).
The opening sequence in prose form: 1.e4 e5, 2.f4 exf4, 3.Nf3 g5, 4.h4 g4, 5.Ne5 Be7. From this position the encyclopaedia records no further canonical continuations — practical play branches into unnamed transpositions or returns to the parent line for alternative ideas.
Use the interactive board above to walk through the moves position-by-position. Click any move in the navigation to step backwards, or use the keyboard arrow keys. For statistical data — how often master-level players have reached this position, White's win-rate, draw frequency, Black's score — see the panel in the right column.
Caissly's coverage of C39 extends through every named sub-variation in this line and across all four locales (English, Spanish, Portuguese, Russian). Where editorial commentary exists for a specific variation it appears as the page body; otherwise the page presents the structural data, board, and statistics as shown here.