A ladder is a situation in which both players play a sequence of pieces in straight lines, often parallel to a nearby edge, to make a straight unbroken chain. Here is an example of a ladder. The picture is of the bottom edge of the board, and red is trying to connect to this edge.
Here red is attacking, and trying to make a connection to the bottom edge, whereas blue is defending and blocking the connection at each stage. If red keeps playing along the second row with a view to connecting to the bottom, then blue is forced to continue playing along the first row if blue wants to prevent the connection.
Ladders often occur close to an edge of the board. The edge in question will usually belong to the attacking player, and the attacking player's chain will almost always be parallel to the edge and further from the edge than the pieces of the defending player.
In the position above it is red (vertical) to move. For the last few moves red has been laddering along the second row, with blue playing underneath to stop red connecting. But red will be able to force a connection to the bottom anyway, because of their ladder escape piece on the very right of the second row:
When the ladder reaches this ladder escape piece, blue can no longer block the connection.
Red could instead have stopped laddering to the right and laddered to the left instead:
but this does not help red to connect to the bottom edge, because on this side of the board red had no ladder escape and cannot break through.
The ladder above is called a second row ladder because the pieces of the attacker (in this case, red) are all on the second row of the board. A second row ladder is the most aggressive kind of ladder to defend against. Ladders can form on other rows too. Here is an example of a third row ladder forming.
Again red wants to connect to the bottom, and blue is defending against this connection. This time red will not succeed in connecting to the bottom, because the red pieces on the right do not form a 3rd row ladder escape, and if red continues to press then blue will be able to successfully block. For example:
Blue has successfully stopped the ladder from connecting.
It is important to recognise some basic positions where a player can force a ladder to occur:
Sometimes it is important to say exactly how close to the edge a ladder is. A second row ladder is a ladder where the attacking pieces are on the second row -- just one row from the attacker's edge. A third row ladder is a ladder where the ladder's attacking pieces are on the third row. One could in theory continue this pattern forever but in practice one rarely talks about fifth or higher row ladders. This is because even though these ladders do sometimes form, the general intention by the attacker is typically not to connect to the edge: the attacker may instead want to try to connect to another group of their own pieces.
Another reason why ladders much higher than the fourth row are not often considered is that if a ladder is sufficiently high, the defender can just ignore it and play elsewhere, and the attacker may not be able to instantly connect. This means that for a sufficiently high ladder it seems impossible to formulate a notion of a ladder escape as the defender can ignore the ladder and play in the escape area without losing immediately.
What every player should know
Players should be able to recognise when ladders are forming, and be able to predict what will happen at the end of them without playing them out. Players should know the basic ladder escapes for second and third row ladders. Then players should learn how to create their own ladder escapes by understanding the basic ladder escape fork trick.
There are three ways for the attacking player to "win" in a ladder situation:
- Making use of an existing ladder escape piece
- Creating a new ladder escape with a Ladder escape fork