Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nf6/3. Nxe5/3...Nxe4/4. Qe2/4...Nf6

This appears to protect Black's knight, but in reality loses their queen. This famous trap, sometimes called the "copycat trap", has ensnared countless amateurs. Better was 4...Qe7, the Kholmov gambit.

The problem for Black is that 5. Nc6+ is both an attack on Black's queen and a discovered check. However Black stops the check, 5...Be7 or 5...Qe7, White's knight takes the queen next.

Pedro Damiano (1480–1544) describes this line. He writes (in Renaissance-era Italian):^[1]

& se lui giocara il cauallo del Re a tre case del delfino^[2] del Re, tu li pigliarai la Pedona del Re co il Cauallo, & se lui te pigliara la tua con il cauallo, giocha la donna denanzi al Re, & se lui leuara il Cauallo li darai scacho per la Donna in discoperta giocando il Cauallo alla terza casa del delfino suo della donna.

& if he plays the king's knight three squares from the king's bishop (2...Nf6), you will take the king's pawn with the knight (3. Nxe5) & if he takes yours with the knight (3...Nxe4), play the queen in front of the king (4. Qe2), and if he removes the knight (4...Nf6??) you will give him discovered check with the queen by playing the knight to the third square of his queen's bishop (5. Nc6+).

This is described in chapter two of Damiano's book (chapter one explains how the pieces move), which is one of the earliest books ever written on the modern formulation of the game. Therefore this trap might be, literally, the oldest trick in the book.