Morphy's Gambit Invitation
Paul Morphy had a pet move order against the Sicilian defense - 1. e4 c5 2. d4 cxd4 3. Nf3. He played this quite regularly, but very few players since have followed his example. Nowadays, when white plays 2. d4 it is because the intended followup is 3. c3, entering the dangerous Smith-Morra Gambit. After 3. Nf3, black has the choice to transpose into several main lines of the open Sicilian, and in many of Morphy's own games this is exactly what happened. Louis Paulsen played 3.. e6 in the finals of the 1st American Chess Congress in 1857, and Adolf Anderssen played 3.. Nc6 in the most famous game from their 1858 match. So if the opening doesn't lead to unique play, then what benefit did Morphy see in this strange move order? And why don't more players play this line today?
The point of 3. Nf3 is that if black is feeling bold enough (or simply doesn't know any better), they may enter into a very dangerous gambit line with the move 3.. e5. This continuation looks very tempting, since black defends the (extra) d4 pawn and claims space in the center. Notice that 4. Nxe5 is not possible due to 4.. Qa5+, winning the knight. For many of Morphy's opponents in the mid-nineteenth century, these benefits would have made the gambit irresistible, but, as will become clear in the remainder of this post, the pawn is certainly not worth the trouble.
Morphy likely came across this move order while studying a famous match between Adolf Anderssen and Daniel Harrwitz (Breslau, 1848). Anderssen played the invitation in two of his five games with white, winning game seven and losing game 9. Harrwitz accepted the pawn in both games.
In game 7 of the match, Anderssen tried an early f4 pawn break, attacking the central pawn chain, and ganged up on the f7 pawn with the moves 4. Bc4 and 5. Ng5. Anderssen exposed black's king while still in the center and, superficially at least, won a brilliant attacking game. However the engine believes that black had the superior position up until Harrwitz's last move 27.. c5, although even here white has more work to do to prove the win. Play might have continued 28.. Kc7 29. Qb7+ Kd8 30. Nc6+ Qxc6 31. Qxc6 Rc8 where material is nearly even but the position is winning for white due to black's exposed king.
Of the 14 games in which Morphy's opponent played the Sicilian defense, Morphy played the intivitation move order 5 times. The invitation was only accepted in two games: first against Paul Journoud and then as part of a blindfold-simultaneous display against Jean-Louis Preti. Morphy won both games handily and played the themes of the position quite differently than Anderssen had. In both games, Morphy inserts a c3 pawn break at the earliest opportunity. Play then takes on the character of a sort of delayed Smith-Morra gambit, in which black has already commited to a pawn on e5. This leaves a glaring hole on d5, and exposes the a2-g8 diagonal to a battery of white's bishop and queen. In the modern Smith-Morra, black almost universally plays the pawn to e6 in order to avoid precisely these weaknesses. In Morphy's game against Journoud, the queen/bishop battery is so effective that there is little black can do to save the f7 pawn as early as move 6. Morphy conducts the rest of the attack with characteristic accuracy.
Not much needs to be discussed in the game against Preti. Black's 4.. Bb4+ is an almost game-ending blunder since Morphy's continuation (recapturing on c3 with the pawn rather than knight) guarantees black will lose the e5 pawn with yet another tempo loss against the f7 pawn. Once black chooses to retreat the bishop to b6 on move 9, Morphy commandeers the a3-f8 diagonal with his dark-square bishop (a theme more commonly seen in the Evan's Gambit). The rest is a slaughter.
It isn't quite fair to say that Morphy's gambit invitation is a "quirky" or offbeat move order, since the theory of the Sicilian defense was not nearly as developed in the nineteenth century as it would become in the twentieth. Who was to say in the year 1858 that 2. d4 and 3. Nf3 would not become the preferred move order? It has no clear downsides, other than that white is offering to play a pawn down. But if a player is comfortable playing a mainline open Sicilian, while also every once in a while playing an improved version of the Smith-Morra gambit, why not?
