Tesuji · 桂香の手筋
Two pieces that only go forward, and are therefore all about timing: too early and they are lost, too late and they are irrelevant.
The knight jumps and the lance runs, and neither can come back. That makes them poor defenders and excellent attackers, as long as the square they land on is one they can stay on. Their techniques are ways of making sure of that.
What. A knight dropped so that its two forward squares hold two enemy pieces: a fork.
Why. The knight attacks two squares and nothing else, so a fork is what it is for. The name is a joke about the shape: two legs and a knight in between.
When. Whenever two enemy pieces stand on the same rank two files apart, with the square two ranks below them empty and out of reach of their pawns.
What. A knight dropped one rank short of where it wants to strike, out of reach, so that it threatens to jump next move.
Why. A knight dropped where it attacks at once is usually attacked at once, by a pawn, and it cannot retreat. One rank back it is safe and the threat is still there. The proverb about knights that jump too high being pawn food is the same lesson from the other side.
When. Against a castle: drop the knight where a pawn cannot reach it and where its jump lands on a general or beside the king.
What. A lance dropped on a file with two enemy pieces on it, attacking the nearer one and, through it, the farther one.
Why. If the near piece moves, the lance takes the far one. If it stays, it is lost. The name is from dengaku, tofu grilled on a skewer.
When. A gold or silver standing in front of a rook or the king on the same file, with the file behind them open to your side.
What. Dropping the lance as far back as possible on the file it attacks.
Why. A lance controls the whole file in front of it. Dropped far back it reaches every square up to its target and cannot be attacked by the pieces it aims at; dropped close, it wastes its reach and can be captured.
When. Whenever the file is open up to the target and the far drop is legal.
What. The mistake, given its own proverb: a knight that jumps into the enemy camp with no support and is attacked by a pawn.
Why. It cannot retreat and the pawn costs the defender nothing. The knight is lost for a pawn, and the attack with it.
When. Never. The cure is the held-back knight above, or a pawn pushed first to take the square the enemy pawn would use.
The app’s review marks the moment a game turned and says what was better. Often the better move is one of these.