Double Wing Attack
In shogi, Double Wing Attack or simply Wing Attack or Centre Game is a Double Static Rook opening in which both sides directly advance their rook pawns forward on the second and eighth files toward their opponent's bishop often with the first several moves on each side being identical or very similar.
Double Wing Attack, which has been played since the Edo period, has been known as a strategy prone to fierce battles due to the lack of a well-developed joseki. However, with the development of computer shogi in the late 2010s including programs such as AlphaZero adopting Double Attack, there has been further progress in the josekis for this opening, which has led to its adoption in most professional title games in 2021 highlighting its importance.
History and general discussion
The Double Wing Attack is one of the most traditional openings dating back to over 250 years ago. Originally, unlike the Yagura openings, in which piece positioning advances by blocking the bishop diagonals, all ways in which the piece positioning proceeds without closing the bishop diagonals received the name aigakari, which has been traditionally translated to English as Double Wing Attack. Later, the strategy of exchanging bishops first and then proceeding with the piece positioning began to be called Bishop exchange, while the strategy of capturing the pawn on 34 after exchanging rooks once both bishop diagonals have been opened began to be called Side pawn capture, openings that are now considered independent of aigakari.Double Wing openings have two general variations. The first one has both bishop diagonals open while the second type has bishop diagonals closed. The open bishop diagonal variations were most common historically being played from the 1700s and throughout the first part of the twentieth century.
However, in modern shogi, the term Aigakari typically refers to the closed bishop diagonal variations. One reason is that the open bishop diagonal position shown in the adjacent diagram most often develops into a Side Pawn Capture opening instead an open bishop diagonal variation of Double Wing. This a major change from past centuries where Side Pawn Capture openings were uncommon as they were considered to be inferior strategies. In the second half of the 20th century, Side Pawn Capture was recognized as a sound opening – eventually becoming one of the most popular Double Static Rook opening among professional players in the 21st century. Thus, a present-day Double Wing opening typically arises when the rook pawns are traded off the board first and only after this are the bishop diagonals opened, which prevents the Side Pawn Capture opening possibility. Consequently, the open bishop diagonal variations of Double Wing are not commonly played by professional players.
During the Edo period the common joseki for Double Wing Attack consisted of advancing the rook pawn after opening the bishop diagonals, and after exchanging pawns, retreating the rook without capturing the side pawn. At the beginning of the Heisei era, the main line became to advance the rook pawns without opening any of the bishop diagonals, and then to retreat the rook after exchanging the pawns. However, starting in the second half of the 2010s, it became more frequent to delay the rook pawns exchange, without doing so immediately.
Traditionally, the two most common positions to which the rook retreated have been R-26 and R-28, but in recent years, the R-25 variation of Double Attack has also appeared in official tournaments. From this point on, several variants are possible, such as Twisting Rook on the left of the board, or Climbing Silver or Reclining Silver using the right silver, which require both players to manage a wide range of moves and imagination. There is a wide variety of strategies, from quick attacks in which both players make use of their pawns in hand, to slow games in which both players castle their kings.
Closed bishop diagonal variation
The initial aim of the Double Wing Attack to threaten each opponent's bishop and to exchange the rook pawns activating the rook.From the start of the game, the pawn at the head of each bishop is undefended. By advancing each player's rook pawn, each player aims for their opponent's bishop head. Then, the initial strategy involved is to provide the head of the bishop with adequate defense and/or give the bishop an escape route from the advancing pawn.
1. P-26 P-84, 2. P-25 P-85. Following the joseki, both sides advance their rook pawns to the middle rank 5.
3. G-78 G-32. Then, golds are moved to defend each bishop's head.
Note that the head of the bishop should be defended.
An alternative option is to advance the side or edge pawn allowing the bishop to escape, which leads to a different set of josekis.
Another alternative is for Black to play a Floating Rook strategy and prevent White from making a pawn exchange, although Black's Rook becomes somewhat exposed.
4. P-24 Px24, 5. Rx24. Next, Black initiates a pawn attack on the second file leading to a pawn exchange involving the rook.
5....P*23. White responds by dropping a pawn to 23 to push Black's rook back.
After move 10 of Double Wing Attack, the joseki branches off into different variants depending on which square the rook moves down to.
Protecting the bishops
After advancing the rook pawns in the first four moves, it is important for both players to protect the bishop's head with a gold rather than immediately pushing their rook pawns again. If either player ignores protecting the bishop after move 4, their bishop may get trapped by a pawn drop according to the famous josekis explained below.Blunder: Black's failure to defend
5.P-24. This sequence of moves is known as the 5-Move Bomb.If Black continues advancing their rook pawn for an attack at 23 instead of defending with a gold as recommended by joseki, after a pawn exchange on the second file involving the rook, White can start a counterattack by advancing their pawn on the eighth file.
Once Black captures White's pawn at 86, rather than recapturing Black's pawn with their rook, White can instead drop a pawn at the bishop's head. Black's bishop is now trapped.
Although Black can also attack White's bishop with a pawn drop, White now has the initiative and will capture Black's bishop first.
After Black captures White's tokin at 88 with a silver, with a bishop in hand, White can fork Black's rook and king pawn by dropping their bishop to 35. At this point, the choices for Black's rook are to either retreat or attack White's bishop. If Black's rook retreats to rank 8, then White can promote their bishop to a horse at 57.
From here, Black can finally capture White's bishop.
Rook capturing tokin variant
After move 17, White must remove the threat of Black's tokin on 22.Aono and Kitao recommend taking the tokin with the rook, which is defended by a silver.
From here, Black may exchange rooks.
But, White is in a better position.
Silver capturing tokin variant
Kitao suggests that taking the tokin with White's silver after move 17 is an inferior move. The reason is because Black will drop their bishop to 45 threatening to promote at 63 and further attack White's camp.At this point, White needs to defend 63. However, a gold can't be used for this purpose because that gold would come between the rook and the silver on rank 2 allowing Black to take the silver for free. Therefore, the suggested move is to use the rook to defend both 63 and 22.
Black now drops a pawn to put the king in check. This move tries to force White's rook to capture the pawn at 52 with White's rook, which will allow Black to successfully promote their bishop at 63 and attack White's rook.
Kitao considers this position uncertain compared to the position in which the rook captures the tokin.
If White uses a gold to capture the checking pawn, then the rook's defense of the silver will be blocked allowing Black to capture the silver.
However, Hosking has a different suggestion which Kitao does not consider.
Hosking's silver variant
In contrast to Aono and Kitao, Hosking recommends the silver taking the tokin along with the defense of this silver as shown below.If White captures the tokin with the silver, Black can now use their newly obtained bishop in the next move.
Black can drop their bishop to 45 attacking 63.
If White tries to defend 63 with another piece now, the rook's defense of the silver on 22 will be blocked allowing Black to capture the silver on 22. Thus, Hosking's solution to defend the silver with a gold.
Black's bishop can promote, but White can attack the bishop with a gold now.
Later White may capture more of Black's pawns with either their rook or horse leading to a stronger position for White.
Ignoring White's counterattack
If Black entertains the possibility of ignoring White completely and continuing their attack by dropping a pawn at 23 to attack White's bishop after move 6, the result stills favors White.Both White and Black's pawn can advance and promote, and Black captures the bishop first. White recaptures the tokin with a silver. Since White's silver at 22 is defended by their rook and Black has no more pawns to drop, Black's best move is to defend against White's attack by retreating to rank 8. Otherwise, White will capture both Black's bishop as well as Black's silver and promote their rook at the same time.
With Black's rook defending 88, the number of pieces in an exchange is even: White's tokin and rook vs Black's silver and rook. However, White can now drop a dangling pawn on 86 which threatens to promote on 87 attacking Black's silver.
At this point, White will capture Black's bishop and break through their camp in future moves leaving Black in an inferior position. Black cannot save their bishop and will probably lose either their knight or silver when White's dangling pawn promotes. There is also the additional risk of White's rook promoting on the eighth file. Although Black was able to get a bishop, White has Black's bishop and also has more captured pieces.