What is tennision gambit?

The Tennison Gambit is a chess opening that starts with the moves 1.e4 Nf6 2.Ne5 d6 3.Nxf7. It is a rarely played and aggressive opening, aiming to sacrifice a knight early in the game in exchange for quick development of the queen and bishop. The Tennison Gambit is named after its creator, Cecil Delmar Tennison, an American amateur chess player who lived in the late 19th and early 20th centuries. It is not commonly played in modern chess, as it is considered to offer Black too much counterplay, but can still be surprising for opponents who are not familiar with it.