Double Wing Attack

In shogi, Double Wing Attack or simply Wing Attack (相掛かり aigakari) is a Double Static Rook (相居飛車) opening in which both sides play Static Rook (居飛車) by directly advancing their rook pawns (歩) forward toward their opponent's bishop (角) with the first several moves on each side being identical or very similar.

This is one of the most traditional josekis dating back to 200 years ago.

Initial positioning

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 (2c for White, 8g for Black) is undefended. By advancing each player's rook pawn (at 8c for White, at 2g for Black), 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-2f P-8d, 2. P-2e P-8e. Following the joseki, both sides advance their rook pawns to the e rank.

3. G-7h G-3b. Then, golds are moved to defend each bishop's head.

Note that the head of the bishop should be defended. (See: § Protecting the bishops below.) 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-2d ... Px2d, 5. Rx2d .... Next, Black initiates a pawn attack on the second file leading to a pawn exchange involving the rook.

5. ... P*2c. White responds by dropping a pawn to 2c 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. (See § Further strategy branches below.)

Protecting the bishops

After advancing the rook pawns in the first four moves (1. P-2f P-8d, 2. P-2e P-8e), 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.

(A similar issue occurs in a Bishop Exchange opening where if bishop's head is not protected by a gold, then a pawn drop can occur.)

Inferiority of silver

Using a silver to defend the head of the bishop is considered a bad formation (悪形 akukei) even though it appears somewhat similar in that the silver can defend the head of the bishop.^[1][2] However, a silver cannot defend from the sides leaving the bishop without any direct connection to a defending piece. 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 the bad bishop–silver formation, White can now open their bishop's diagonal.

This move by White also prevents Black from opening their diagonal since doing so would lead to White capturing Black's bishop without penalty. Furthermore, this position cannot be easily repaired since Black's silver cannot retreat to its original position.

White's failure to defend

According to joseki, when both Black and White defend their bishops with a gold, after White exchanges their rook pawn, Black is recommended to drop a pawn to 8g for move 15 (see above).

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.^[3]

After White attacks 8g and the subsequent pawn exchange, joseki recommends that Black start a counterattack at the head of White's bishop (2c) by the rook pawn rather than trying to defensively attack White's rook. (The reason for this is that White's rook could simply fall back to a floating rook position on 8d thus preventing Black from making a pawn exchange on the second file and then controlling the flow of the game.)

After Black's counterattack, White will capture Black's pawn.

This pawn capture by White allows Black to drop a pawn (obtained from the eighth file pawn exchange) at the head of White's bishop.

White can follow suit and also drop a pawn at the head of Black's bishop.

But, Black captures White's bishop first.

After White recaptures Black's tokin on the second file, Black drops the bishop on 7e creating a rook–pawn fork.

(Although it's possible that Black could also protect their bishop by capturing White's pawn with their gold [8. Gx7g], this is a bad move since White's rook will be able to promote after taking Black's gold [8. ... Rx7g+].)

White now has a choice between retreating their rook back to their camp at 8b or attacking Black's bishop.

If the bishop on 7e is attacked (as shown here, R-8e), then Black will promote their bishop on fifth file.

White's rook can continue to attack the bishop (R-5e), but Black can continue eluding capture with a sidestep to the fourth file.

White's rook can now promote (R-5g+), but Black can defend their king with a pawn drop (P*5h).

White can capture another pawn (+Rx4g), but Black can gain a knight (+Bx2a).

This position is thought to still favor Black.

Black's failure to defend

If Black continues advancing their rook pawn for an attack at 2c 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.^[4]

Once Black captures White's pawn at 8f, rather than recapturing Black's pawn with their rook (as happens in the recommended joseki), White can instead drop a pawn at the bishop's head (P*8g). 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 8h with a silver, with a bishop in hand, White can fork Black's rook and king pawn by dropping their bishop to 3e. At this point, the choices for Black's rook are to either retreat or attack White's bishop. (Ignoring the bishop attack may lead to losing the rook.) If Black's rook retreats to the h rank (as shown in the diagram), then White can promote their bishop to a horse at 5g.

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 2b.

Aono and Kitao recommend taking the tokin with the rook, which is defended by a silver.

(Hosking suggests a variant in which the silver captures the tokin. See below.)

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.^[5] The reason is because Black will drop their bishop to 4e threatening to promote at 6c and further attack White's camp.

At this point, White needs to defend 6c. However, a gold can't be used for this purpose because that gold would come between the rook and the silver on the b rank allowing Black to take the silver for free. Therefore, the suggested move is to use the rook to defend both 6c and 2b.

Black now drops a pawn to put the king in check. This move tries to force White's rook to capture the pawn at 5b with White's rook (Rx5b), which will allow Black to successfully promote their bishop at 6c and attack White's rook (Bx6c).

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 (Gx5b), then the rook's defense of the silver will be blocked allowing Black to capture the silver (Rx2b).

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 4e (or 3f) attacking 6c.

If White tries to defend 6c with another piece now, the rook's defense of the silver on 2b will be blocked allowing Black to capture the silver on 2b. 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 (since the rook is freed up from its defensive role).

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 2c to attack White's bishop after move 6, the end result stills favors White.^[4]

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 2b 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 the h rank. 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 8h, 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 8f which threatens to promote on 8g 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.

Further strategy branches

After move 10 of Double Wing Attack, the joseki branches off into different variants depending on which square the rook moves down to.

In the Floating Rook variant, the rook moves to 2f.

In the Retreating Rook variant, the rook returns to 2h.

Retreating Rook

Retreating Rook (引き飛車 hikihisha) is an opening following the Double Wing opening proper in which Black's rook retreats all the way back to their camp allowing White to also exchange rook pawns.

Floating Rook

In contrast to the Retreating Rook variant of Double Wing Attack, Floating Rook (浮き飛車) aims to protect the f rank and prevent White from exchanging pawns on the eighth file to get a pawn in hand.

See also

• Shogi opening
• Shogi strategy and tactics

References

Bibliography

• Aono, Teruichi (2009) [1983]. Better Moves for Better Shogi. Translated by Fairbairn, John (2nd ed.). Ishi Press. ISBN 978-4-87187-999-6. 
• Aono, Teruichi (1983). Guide to shogi openings: Shogi problems in Japanese and English 将棋定跡のカギ: 和英 定跡問題集. Translated by Fairbairn, John. 山海堂. ISBN 4-381-00598-8. 
• Hosking, Tony (1997). The Art of Shogi. The Shogi Foundation. ISBN 978-0-95310-890-9. 
• Kitao, Madoka (2011). Joseki at a glance. Translated by Kawasaki, Tomohide. Nekomado. ISBN 978-4-9052-2501-0. 

External links

• YouTube: HIDETCHI"s Double Wing Attack #1