Basic Tactics For Breaking Yagura Castle (2)

Continued from the previous article. 

There is another famous tactic with a knight.

Diag.1

In Diag.1, ▲N*24 is the tactic which is often seen in the endgame of Yagura as well as the previous ▲S*41 and ▲S*52. With △Px ▲Px (Diag.2), it seems like sente lost material, but, the pawn on 24 becomes the basis to attack. While sente has a gold or silver in hand, dropping it on 23 next will be a decisive attack for breaking the castle. Thus, in most cases, gote needs to remove it with △Sx in spite of the silver - knight exchange. After this, it proceeds with ▲Rx △P*23 ▲R-28. 

And, sometimes △N*31 is better than △Sx though the point in front of the king remains as the threat. It depends on the situation which to choose. I think, basically, in case of attempting to attack afterward (to gain a tempo), △Sx should be played, and in case of defending thoroughly without giving pieces, △N*31 should be played.
In addition, in reply to ▲N*24, △G-31 and △G32-42 are also considered unless there is subsequent attack.

Diag.2

If gote has a pawn in hand in Diag.2, with △P*23 ▲Px+ △Gx (Diag.3), gote can absorb the basis on 24. However, this defense doesn't always work well because the shape of the Yagura gets worse instead of gaining a knight, especially against the attack from the side. 

Diag.3

For example, In Diag.4, after ▲N*24 △Px ▲Px, dropping △P*23 is a blunder. There is a mate with ▲Px+ △Gx ▲Rx21+ △Kx ▲Rx23+ △P*22 ▲G*32 (Diag.5). The line from ▲Rx21+ is often overlooked. In general, the rook on 1st rank or 2nd rank in the opponent's camp has a big influence to the castle, therefore the player on the defense side needs to be careful about the various tactics to attack.

Diag.4

Diag.5

Then, △N*31 also get into danger with ▲P-23+ △Gx (in case of △Nx, ▲P*24 is severe) ▲Rx31+ △Kx ▲Rx23+ (Diag.6). Promoted the rook near the king, it's hard to protect even if the defense side gains material. 

Here, △Sx ▲Rx △P*23 ▲R-28 is a common line.

Diag.6

When having a knight in hand, the attacker should play with the tactic from ▲N*24 in mind. On the other hand, the defender has to choose the move suitable for the situation, otherwise the castle would be broken immediately.