Category - Closed Game
Opening Move Sequence - 1 d4, 2 e3, 3 f4, and 4 c3, or similar.
ECO Codes - D00, A03, A45
Stonewall Attack is more of a position that White achieves than an opening with specific sequence of moves. White places pawns at c3, d4, e3, and f4. In most cases White will also place the Bishop at d3 as well. The same position may be reached from many different openings, coming under Queen's pawn game openings. It does not matter how Black plays while White sets up this position. Black too can achieve a similar formation with pawns at c6, d5, e6 and f5 through the Dutch Defense.
Stonewall Attack, as can be assumed from its name, is a highly defensible position. It also allows White the initiative to start a devastating attack if Black does not play vigilantly. The whole attack is carried out by bring the required pieces to specific positions rather than by playing tactically to gain positional advantages as happens in usual play. White's attack will be characterized by advance of the pawn on g file, moving Rook to h3, and a Bishop sacrifice at h7. All this have to be carried out in timely fashion however. This attack on Black King does not need the support of White's Knight and Bishop on the Queen side so they are usually not developed.
The fact that Stonewall Attack is not based on tactical play means it can be used with effect against Chess playing computers which usually analyses and evaluates their positions and moves along tactical lines. Computer programs like that will probably miss the attack until it is well under way.
Main weaknesses of Stonewall Attack for White are the weak point at e4 square and the non development of White's Queen-side or dark squared Bishop. In fact the Bishop is shut in by White's own pawns.
Weaknesses mentioned above can be exploited by Black when defending against Stonewall Attack. If Black plays correctly, the effect on White will be so debilitating that this opening is hardly ever seen in tournament play nowadays. However it is played by players at lower levels. On the other hand the Black equivalent of Stonewall Attack, the Stonewall Defense Variation in Dutch Defense is still played at all levels of chess.
Black's options against Stonewall Attack include fianchettoing either one or even both Bishops and taking control of center through pawns. Black can also play b6 followed by Ba6 in order to exchange the White's Bishop at d3.
Stonewall Attack is hard to classify under the ECO or Encyclopedia of Chess Openings because that classification is based on the opening sequence of moves and Stonewall Attack does not have a specific sequence of moves. For instance it comes under both D00 Closed Game opening starting 1 d4 d5, and under A03 and A45 as well, which deal with a Flank opening called Bird's Opening starting with 1 f4.
