On this blog I refer to 1.e4 e5 2.Nf3 Nc6 3.Bc4 h6 as the Semi-Italian Opening, a name given to it in Chess Master Vs Chess Amateur(1963), byMax Euwe and Walter Meiden. Here is what the authors say about Black's third move (I have changed the notation from English descriptive to algebraic.
This is a favorite move of the weaker amateur. He fears some future attack by the White QB (Bg5, for instance) or by the White KN (Ng5), and, before the White QB is even able to move, he plays the precautionary 3...h6. In certain positions, such a precautionary move is occasionally necessary, but in this position, not only is it not necessary, but it consumes valuable time. This puts Black one move behind White in the type of opening where tempi are of greatest importance. Instead of meeting the enemy's rapidly mobilizing forces with armed soldiers (i.e., by bringing out his pieces), Black only loses time and force, and, without realizing it, even weakens his defensive wall...After 4.d4 exd4 they write
Black must take, as we shall see by an analysis of the most plausible alternate reply 4...d6: 5.dxe5 dxe5 6.Qxd8+ and (a) 6...Kxd8 7.Bxf7, etc., or (b) 6...Nxd8 7.Nxe5. White could act even more energetically by playing 6.Bxf7+ Kxf7 7.Nxe5+, and Black is in great trouble, for (a) 7...Nxe5? 8.Qxd8 or (b) 7...Ke7 8.Ng6+, or (c) 7...Ke8 8.Qh5+ Ke7 9.Ng6+. After (d) 7...Kf6, the continuation is less clear. This does not mean that the sacrifice would be incorrect, since after 8.Nd3, White has two Pawns for a piece and the Black King is badly placed. On the other hand, a safe win of a Pawn as in the other variations, might be preferable.The authors then look at 5.c3 and 5.Nxd4, and there I shall leave them.
I went back to Chess Master vs Chess Amateur after I began thinking about how to transform the game to the Semi-Italian Jerome Gambit. I usually play 4.0-0 (then, after 4...Bc5, I play 5.Bxf7+), but I keep wanting to look at 4.Nc3 and other possible moves.
Hmmmm.... What about the normal 4.d4 that Euwe and Meiden recommend? How does that fit in for the Jerome Gambiteer?
Well, there are 300 games in The Database with the line 4...exd4 5.Bxf7+, but before we go there, let's take a look at the mistaken 4...Nxd4? (perhaps Black plays the Blackburne Shilling Gambit and gets carried away here).
Even someone who does not play the Jerome Gambit should start reaching toward his King's Bishop...