Chess Opening Theory/1. e4/1...e5/2. f4/2...exf4/3. Nf3/3...g5/4. h4/4...g4

King's Knight Gambit

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Common moves:
5. Ne5 - Kieseritzky Gambit
5. Ng5 - Allgaier Gambit

White's knight is attacked. Although there are some King's Gambit positions where White can ignore this attack and carry on developing, this isn't one of them.

• 5. Ne5 is the Kieseritzky Gambit, which can be considered the main line of the whole King's Gambit. White targets f7 and g4, in the hope of recovering her lost pawn and leaving Black with weak pawns on f4, f7 and h7. But while that knight is going on a tour of the board, Black is catching up on development with moves like ...d6 and ...Nf6, and even if Black does end up with doubled isolated f-pawns, the one on f4 is going nowhere and remains a thorn in White's side.
• 5. Ng5 is the Allgaier Gambit. Black can now trap the knight with 5...h6, forcing it to sacrifice itself on f7 to displace the Black king. How well this typically works can be illustrated by the fact that the Kieseritsky Gambit is statistically one of the most terrible openings in the White repertoire, but it's still about ten times as popular as the Allgaier Gambit.

5.Nd4 is just going to give away a tempo to 5...Bg7, and 5.Nh2 undefends h4 with dire consequences.

Theory table

For explanation of theory tables, see theory table and for notation, see algebraic notation..

1.e4 e5 2.f4 exf4 3.Nf3 g5 4. h4 g4

	5	6
Kieseritzky Gambit	Ne5 Nf6
Allgaier Gambit	Ng5 h6	Nxf7 Kxf7

References

• Fundamental Chess Openings (2009). Paul van der Sterren. ISBN 1-906454-13-2.

• The King's Gambit (2013). John Shaw. ISBN 978-1-906552-71-8.

• "The King's Gambit". The Gambiteer's Guild. Retrieved 25 Jul 2014.