Deutz Gambit

The Deutz Gambit, also called the Max Lange Gambit, arises when White castles on move four and answers 4...Nf6 with 5. d4. The d-pawn can be taken by three different black units. With the king already safe, White aims to open the center, free the dark-squared bishop and attack before Black has castled. The engine rates the position as roughly balanced, but White scores well in online games.

The most frequent capture, 5...exd4, allows 6. e5, transposing to the Max Lange Attack of the Scotch Gambit. There a knight retreat costs time, and 6...d5 7. exf6 dxc4 8. fxg7 favors White. Theory rates 5...Bxd4 as the best reply, giving up the bishop for a knight. After 6. Nxd4 Nxd4 White chooses between two continuations. The pin 7. Bg5 can be neutralized by accurate defense that forces a level, queenless endgame. The move 7. f4 hits e5 and keeps the queens on, and Black should hold the pawn with 7...d6. The rarer 5...Nxd4 is considered an error because 6. Nxe5 brings knight and bishop to bear on f7.