Fortress opening

Fortress (矢倉 or 櫓 yagura) is both a Static Rook opening (矢倉戦法 yagura senpō) and a castle in shogi.

Double Fortress variation
after 32 moves
☖ pieces in hand: –
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香桂     桂香1
 飛 銀  金王 2
歩  歩 金銀歩歩3
 歩歩角歩歩歩  4
         5
  歩歩歩 歩  6
歩歩銀金 歩銀歩歩7
 玉金角   飛 8
香桂     桂香9
☗ pieces in hand: –
A common variation. Both players' kings are fully inside Fortress castles. Black has advanced their right offensive silver to 37 while White's bishop is positioned on 64.

It is usually played in a Double Static Rook opening, which is often a Double Fortress opening. However, it may also occur in different Double Static Rook openings such as Fortress vs Right Fourth File Rook.

The Fortress castle (矢倉囲い yagura gakoi), which is the defining characteristic of Fortress games, was considered by many to be one of the strongest defensive positions in Double Static Rook games in the 1980s.[1]

The term yagura is the Japanese word for a tower-like structure in traditional Japanese castles.

Double Fortress
Double Fortress
☖ pieces in hand: –
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香桂   王 桂香1
 飛 銀金 金  2
歩  歩  銀歩歩3
 歩歩角歩歩歩  4
         5
  歩歩歩 歩  6
歩歩銀金 歩銀歩歩7
  金角   飛 8
香桂 玉   桂香9
☗ pieces in hand: –
Main article: Double Fortress

The most commonly encountered Fortress strategies occur in Double Fortress games where both players use a Fortress formation.

Historical Fortress

Earlier josekis for Fortress in the Edo period (usually spelled 櫓 at that time) were very different from the current josekis.

For instance, in one variation, it is White who delays pushing their rook pawn (whereas Black delays the rook pawn push in the modern era) and an early bishop trade occurs before both players' kings are moved into their castles.

vs Right Fourth File Rook
Fortress vs Right Fourth Rook
☖ pieces in hand: –
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香桂 金王金銀桂香1
   飛   角 2
歩 歩 歩歩 歩歩3
 歩  銀 歩  4
   歩     5
  歩歩歩  歩 6
歩歩  銀歩歩 歩7
 角金銀   飛 8
香桂  玉  桂香9
☗ pieces in hand: –
Main article: Fortress vs Right Fourth File Rook

vs Snowroof
Fortress vs Traditional Snowroof
☖ pieces in hand: –
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香桂  角王 桂香1
 飛  金 金  2
歩   銀銀 歩歩3
  歩歩歩歩歩  4
 歩     歩 5
  歩歩歩    6
歩歩銀金銀歩歩 歩7
  金角   飛 8
香桂玉    桂香9
☗ pieces in hand: –
Position after move 32 in an Ōza match between Habu (Black) and Nakamura (White) on September 18, 2013.

The Snowroof strategy can be played against a Fortress opponent.

Modern Snowroof vs Fortress
☖ pieces in hand: –
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香桂   王角桂香1
 飛 銀  金  2
歩  歩 金銀歩歩3
  歩 歩歩歩  4
 歩     歩 5
  歩歩 歩歩  6
歩歩角銀歩銀桂 歩7
  金 金    8
香桂  玉  飛香9
☗ pieces in hand: –
Position after move 29 of Momoko Katou (Black) vs Daisuke Nakagawa (White) August 25, 2017.

Rapid Attack Fortress

Rapid Attack Fortress strategies are characterized by the fact that White will start the fight following Black's blocking of the bishop's diagonal. These are active plans where White wants to avoid a development in which Black takes hold of the initiative. The side playing Fortress aims at building up a position wary of the rival's rapid attack. There are a number of variations:

The rapid attack strategy will vary depending on whether in the fifth move Sente plays P-66 or S-77. For example, both Sitting King Bogin and Right Fourth File Rook are played following P-66, while Central Rook Fortress and Akutsu Rapid Attack Fortress are played following S-77. Yonenaga Rapid Attack Fortress can be played against either.

vs White's Left Mino

1. P-76 P-84

2. S-68 P-34

3. P-66 S-62

4. P-56 P-54

5. S-48 G61-52

6. G49-58 S-32

7. G-67 P-44

8. S-77 G-43

9. B-79 B-31

10. P-36

See also

References
  1. Fairbairn 1984.

Bibliography
  • Aono, Teruichi (2009) [1983]. Better moves for better shogi. Translated by Fairbairn, John (2nd ed.). Ishi Press. ISBN 978-4-87187-999-6.
  • Fairbairn, John (1981). "How to play the fortress opening part 1". Shogi (29): 4–6.
  • Fairbairn, John (1981). "How to play the fortress opening part 2". Shogi (30): 14–15.
  • Fairbairn, John (1984). Shogi for Beginners. Ishi Press. ISBN 978-4-8718-720-10.CS1 maint: ref=harv (link)
  • Hosking, Tony (1996). The art of shogi. The Shogi Foundation. ISBN 978-0-95310-890-9.CS1 maint: ref=harv (link)
  • Kitao, Madoka (2011). Joseki at a glance. Translated by Kawasaki, Tomohide. Nekomado. ISBN 978-4-9052-2501-0.CS1 maint: ref=harv (link)
  • Kitao, Madoka (2013). Sabaki at a glance. Translated by Kawasaki, Tomohide. Nekomado. ISBN 978-4-9052-2510-2.


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