Double Fortress

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Double Fortress
☖ pieces in hand: –
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香      桂香1
 飛 銀  金王 2
  桂歩 金銀歩歩3
 歩歩角歩歩歩  4
歩       歩5
  歩歩歩 歩歩 6
歩歩銀金 歩銀  7
 玉金角   飛 8
香桂     桂香9
☗ pieces in hand: –
Hifumi Katō vs Sōta Fujii 2016 after 38 moves [1]

The Double Fortress (相矢倉 or 相櫓 aiyagura) is a shogi opening in which both players construct Fortress formations.

Contents

Double Fortress games are the most common type of Fortress games found at all levels of play.

Historical Fortress

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

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

In the 1947 Meijin tournament, Masao Tsukada and Yoshio Kimura played an early example of the typical 3. S-77 type of Fortress with 1.P-76 P-84 development found in modern shogi. [2]

Tsukada vs Kimura 1947
up to move 14
☖ pieces in hand: –
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香桂 金王金 桂香1
 飛 銀   角 2
歩 歩歩 歩銀歩歩3
    歩 歩  4
 歩     歩 5
  歩 歩    6
歩歩銀歩 歩歩 歩7
 角   銀 飛 8
香桂 金玉金 桂香9
☗ pieces in hand: –
1. P-76   P-84

2. S-78   P-34
3. S-77   S-62
4. P-26   S-42
5. P-25   S-33
6. S-48   P-85

7. P-56   P-54

1. P-76 P-84 development

3. S-77: Blocking bishop with silver

Fortress
up to move 5
☖ pieces in hand: –
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香桂銀金王金銀桂香1
 飛     角 2
歩 歩歩歩歩 歩歩3
 歩    歩  4
         5
  歩      6
歩歩銀歩歩歩歩歩歩7
 角  Shogi dulh22.svg    飛 8
香桂 金玉金銀桂香9
☗ pieces in hand: –
3. S-77

Blocking White's bishop with a silver (and also defending the eighth file from a possible attack) is an older Fortress joseki, which typically also includes advancing Black's rook pawn.

The more recent joseki advances Black's pawn on the sixth file instead. (See above.)

Classic Fortress 24-Move Set

Classic Fortress
up to move 24
☖ pieces in hand: –
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香桂   王角桂香1
 飛 銀金 金  2
歩  歩  銀歩歩3
 歩歩 歩歩歩  4
         5
  歩歩歩 歩歩 6
歩歩銀  歩  歩7
  金 金銀 飛 8
香桂角玉   桂香9
☗ pieces in hand: –

Classic Fortress 24-Move Set (旧矢倉24手組 kyū yagura nijū-tegumi)

Compared to the New Fortress 24-Move Set , note that the Classic Fortress 24-Move Set is (a) symmetrical where both sides have the same formation and (b) that only Black's formation differs (White's formation is the same in both the old and new josekis.)

Right Gold to 67 variant

Right Gold To 67 (6七金右 roku-nana kin migi)

Spearing the Sparrow
Spearing the Sparrow
up to move 25
☖ pieces in hand: –
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香桂   王角桂香1
 飛 銀金 金  2
歩  歩  銀歩歩3
 歩歩 歩歩歩  4
         5
  歩歩歩 歩歩歩6
歩歩銀  歩   7
  金 金銀 飛 8
香桂角玉   桂香9
☗ pieces in hand: –
25. P-16

Spearing the Sparrow (雀刺し suzume-zashi)

3. P-66: Blocking bishop with pawn

At move 6, White also has an option to play Climbing Silver by advancing their rook pawn to rank 5. (See: White Climbing Silver.)

New Fortress 24-Move Set

Fortress
up to move 24
☖ pieces in hand: –
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香桂   王角桂香1
 飛 銀金 金  2
歩  歩  銀歩歩3
 歩歩 歩歩歩  4
         5
  歩歩歩 歩  6
歩歩銀金 歩 歩歩7
  金  銀 飛 8
香桂角玉   桂香9
☗ pieces in hand: –

New Fortress 24-Move Set (新矢倉24手組 shin yagura nijū-tegumi)

Quick Fortress castling

Fujii Quick castling
☖ 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 歩歩歩  4
       歩 5
  歩歩歩 歩  6
歩歩銀金 歩銀 歩7
   玉   飛 8
香桂角金 Shogi dulh22.svg   桂香9
☗ pieces in hand: –

Quick Fortress castling

White's Fortress Climbing Silver

Silver-37 variations

After the 24-move set of the Fortress opening, one major branch in the Fortress strategies is the Silver-37 set of variations. Many variations are under this parent variation.

Katō variation

Named after Hifumi Katō.

Waki System

Morishita System

The Morishita System delays moving the right attacking silver to 37 early. Instead, it simply moves the bishop to 68 allowing the king to move into the Fortress castle in subsequent moves.

Other development patterns

1. P-76 P-34 2. P-66 patterns

Additionally, earlier Fortress openings in the first part of the 20th century did not follow from the standard 1. P-76 P-84 opening used today and instead developed from mutual opening of the bishop diagonals with 1. P-76 P-34.

Fortress development from Bishop Exchange

A Fortress position may also be developed from a rejected Bishop Exchange opening. For example, after a Bishop Exchange setup, instead of White trading the bishops off the board, White may choose to reject the bishop trade by closing their bishop diagonal. At this point, both players may convert their left side configurations into Fortress castles by pulling their bishops back and moving their silvers to the 77 and 33 squares. Thus, Black may move their bishop to 68 (or to 59 if their king moves to 69 first) allowing their left silver to move to 77. Likewise, White may move their bishop to 33 (usually triggered by Black pushing their rook pawn to 25), move their left silver to 22, move their bishop to 42 allowing their left silver to move 33.

Although possible, this Fortress development is not very common among professional players. When White rejects the bishop trade in this way, it is more common for White to play a Snowroof position while Black switches to a Fortress position instead of a Double Fortress game. [3]

Game example

Hirokazu Ueno vs Keiji Nishikawa 2008. [4]

See also

Bibliography

Related Research Articles

Shogi, like western chess, can be divided into the opening, middle game and endgame, each requiring a different strategy. The opening consists of arranging one's defenses and positioning for attack, the middle game consists of attempting to break through the opposing defenses while maintaining one's own, and the endgame starts when one side's defenses have been compromised.

A shogi opening is the sequence of initial moves of a shogi game before the middle game. The more general Japanese term for the beginning of the game is joban (序盤).

In shogi, castles are strong defensive configurations of pieces that protect the king.

Fortress is both a Static Rook opening and a castle in shogi.

Climbing Silver is a shogi strategy.

In shogi, Third File Rook is a class of Ranging Rook openings in which the rook is positioned on the third file if played by White or the seventh file if played by Black.

Static Rook openings in shogi typically have the player's rook at its start position, which is the second file for Black and the eighth file for White.

Left Silver-57 Rapid Attack or Left Silver-5g Rapid Attack or Left Silver-5g Quick Attack is a fast attacking strategy in shogi used with several different Static Rook openings often played by Black against Ranging Rook positions played by White. It is characterized by moving the left silver from its start position on 79 to the 57 square.

In shogi, Central Rook is a subclass of Ranging Rook openings in which the rook is positioned on the fifth (central) file.

In shogi, Retreating Rook is a variant of the Double Wing Attack opening and joseki in which Black's rook retreats all the way back to their camp after a pawn exchange in the eighth file allowing White to also exchange rook pawns.

Fortress castle

Fortress or Yagura is a castle used in shogi. It is considered by many to be the strongest defensive position in shogi in Double Static Rook games.

Snowroof Static Rook opening in Japanese Chess

In shogi, Snowroof or Snow Roof Fortress is a Static Rook opening that characteristically uses a Snowroof castle.

The Wrong Diagonal Bishop or Parallel-Diagonal Bishop is a shogi opening characterized by a bishop trade followed by dropping the bishop in hand on the 45 square if played by Black or the 65 square if played by White.

In shogi, Bishop Exchange Reclining Silver or Reclining Silver With Bishops Off or Bishop Exchange Sitting Silver is a Bishop Exchange opening that uses a Reclining Silver attacking formation.

In shogi, Spearing the Sparrow is one of the substrategies of the Fortress class of openings. The strategy is basically an edge attack on the first file if played by Black or the ninth file if played by White. The player's rook characteristically moves to the respective edge file to support an attack there along with the right knight, the edge pawn, the right lance, and the bishop.

In shogi, the Morishita System is a strategy used by Black in Double Fortress openings. The strategy was invented by professional player Taku Morishita for which he won the prestigious Kōzō Masuda shogi award. Morishita himself has described it as a way of thinking rather than a specific strategy. Hitoshige Awaji and Teruichi Aono are well known for their efforts to systematize it.

Central Rook Fortress is a Double Fortress shogi opening.

The IshidaOpening is a major variation in Third File Rook openings of the Japanese game of shōgi.

In shogi, King's Head Vanguard Pawn or King's Side Vanguard Pawn is a Static Rook opening.

Double Static Rook positions are shogi openings in which both players use a Static Rook position.

References

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