Kieseritzky Gambit

In chess, the Kieseritzky Gambit is an opening line in the King's Gambit It begins with the moves:
Following Black's attempt to hold the sacrificed pawn by 3...g5, White reacts by immediately undermining the pawn chain. It is one of the main lines of the King's Gambit after 3...g5, and its overall assessment is still unclear but approximately equal. The "Encyclopaedia of Chess Openings" classifies the Kieseritzky Gambit under code C39. C39 is also the code for the Allgaier Gambit, in which White plays 5.Ng5?!, sacrificing the knight for an attack after 5...h6 6.Nxf7 Kxf7. The Allgaier Gambit is considered dubious by modern theory.
History.
The opening now known as the Kieseritzky Gambit was first described by Polerio in the late 16th century; it was also analyzed by Salvio (1604) and Philidor (1749). Greco also included a game with this opening in his 1620 collection. In the first edition of the Handbuch in 1843, 5.Ne5 was considered under the heading of the Allgaier Gambit, but the editors noted that Kieseritzky had contributed significantly to the theory of 5.Ne5, which they advocated as superior to 5.Ng5. The corresponding chapter in the second edition of the Handbuch in 1852 was headed "Allgaier and Kieseritzky's Gambit". Subsequently the name Kieseritzky Gambit came into general use for 5.Ne5.
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