Explanation

In Open Lines for Checkmate, you practiced opening a line to make a move possible. In this level, you'll open lines in situations where the move itself is already possible but a possible check after that move is blocked by an opponent's piece.

Sometimes you can force your opponent to open a line with a capture. Here are some examples:

In the first diagram, you see the situation from the "Open Lines for Checkmate" level. If the rook could move to h7, it would be checkmate, but the black g-pawn is in the way. White can capture the knight, and if Black recaptures, the seventh rank is opened, and the rook can move to h7: 1.Nxh6 gxh6 2.Rxh7#.

In the second diagram, White can move Rh4, but it wouldn’t come with check, because the pawn on h7 would block the check. White can capture the queen with 1.Qxg6. If Black recaptures with 1...hxg6, the h-file is opened, and now 2.Rh4# comes with check and checkmate.

In the third diagram, g6 is an empty square, but White can sacrifice the knight to open the h-file and force checkmate with 1.Ng6+! hxg6 2.Rh4#.

In the fourth diagram, White can play 1.Qg6! to threaten Qxh7#. Black can defend against the checkmate threat with 1...hxg6, but this opens the h-file for 2.Rh4#.

Examples

Black can open the line from h5 to h1 with the knight sacrifice 1...Nfg3+!. White is forced to capture the knight with 2.hxg3, and Black can checkmate with 2...Qh5#.

This combination often includes a deflection of the blocking piece, as in the following example:

White can open the line from a6 to c8 with the queen sacrifice 1.Qxc6+!. Black is forced to capture the queen with 1...bxc6. The pawn is also deflected from protecting a6, and White can checkmate with 2.Ba6#. This is a common way to reach Boden's mate.

Black can open the line from e1 to g1 with the queen sacrifice 1...Qxf2+!. If White replies 2.Kh1, Black can checkmate with 2...Qxf1#. If White captures the queen with 2.Rxf2, the rook is also deflected from protecting e1, and Black can checkmate with 2...Re1#.

Note that the bishop on b6 is pinning the rook, preventing Rf1. This combination also includes clearance, as the queen cleared the way for the rook from e5 to e1. It is a common way to force back-rank mate against the castled king, if the rook on the f-file is the only piece guarding the back-rank, and there is a bishop on the diagonal.

Related motifs

A line can also be opened for the checkmate move (instead of for the checkmate attack).
It is also possible to open a line for a fork attack.