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.
[1] 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.
[2] The Double Wing Attack is one of the most traditional openings dating back to over 250 years ago.
Originally, unlike the Yagura (Fortress) 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 (lit.
Later, the strategy of exchanging bishops first and then proceeding with the piece positioning began to be called Bishop exchange (Japanese: Japanese: 角換わり, romanized: kakugawari), while the strategy of capturing the pawn on 34 (i.e. the 'side pawn') after exchanging rooks once both bishop diagonals have been opened began to be called Side pawn capture (Japanese: 横歩取り, romanized: yokofudori), openings that are now considered independent of aigakari.
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.
This a major change from past centuries where Side Pawn Capture openings were uncommon as they were considered to be inferior strategies.
Consequently, the open bishop diagonal variations of Double Wing (without captured side pawns) are not commonly played by professional players (although they are occasionally seen).
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 (in Black's case), but in recent years, the R-25 variation of Double Attack has also appeared in official tournaments.
From the start of the game, the pawn at the head of each bishop (23 for White, 87 for Black) is undefended.
An alternative option is to advance the side or edge pawn allowing the bishop to escape, which leads to a different set of josekis.
White responds by dropping a pawn to 23 to push Black's rook back.
P-25 P-85), it is important for both players to protect the bishop's head with a gold rather than immediately pushing their rook pawns again.
If Black's rook retreats to rank 8 (as shown in the diagram), then White can promote their bishop to a horse at 57.
Aono and Kitao recommend taking the tokin with the rook, which is defended by a silver.
[4] The reason is because Black will drop their bishop to 45 threatening to promote at 63 and further attack White's camp.
If White captures the tokin with the silver, Black can now use their newly obtained bishop in the next move.
However, White can now drop a dangling pawn on 86 which threatens to promote on 87 attacking Black's silver.
Black cannot save their bishop and will probably lose either their knight or silver when White's dangling pawn promotes.
However, if Black defends their bishop with gold but White does not and instead continues with a premature advance of their rook pawn, joseki recommends a different strategy.
White now has a choice between retreating their rook back to their camp at 82 or attacking Black's bishop.
For instance, in the adjacent diagram, Black moves the left silver beside the bishop to prepare for White's attack from their advancing rook pawn.
Due to Black's poor bishop–silver formation, White will now open their bishop's diagonal to take advantage of this situation.
In contrast to the Retreating Rook variant of Double Wing Attack, Floating Rook (浮き飛車) aims to protect rank 6 and prevent White from exchanging pawns on the eighth file to get a pawn in hand.
A Floating Rook variant of Double Wing Attack developed by Yasuaki Tsukada.
However, it was the Double Wing variation used up until a little after World War II and early versions of it were used starting from 1625.
The Old Double Wing opening became obsolete after central pawn push strategies were replaced by pushing pawns on the fourth file with the Reclining Silver strategy (sixth file for White).
However, hundreds of years ago, this positioning with all major pieces activated was very typical of the Double Wing Attack.