Block escape square (2 moves)

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To checkmate the king, all escape squares have to be guarded by your own pieces, or blocked by the opponent's pieces. Usually it is easier to guard the escape squares, but sometimes it is possible to force your opponent to block them.

Explanation

To checkmate the king, all escape squares have to be guarded by your own pieces, or blocked by the opponent's pieces. Usually it is easier to guard the escape squares, but sometimes it is possible to force your opponent to block them.

How can you force your opponent to block an escape square? The two most common ways are:

  • Giving a check that the opponent is forced to block, thereby also blocking an escape square.
  • Sacrificing a piece on an escape square with check. The opponent has to capture the piece, and by doing so blocks that escape square.

The following diagram illustrates both ways:

In the first diagram, if White plays 1.Qf6+? immediately, the king can escape to g8. But White can instead start with 1.Qf8+!, forcing Black to block the check with 1...Bg8. Now White can play 2.Qf6# and it is checkmate, because the escape square g8 is blocked.

In the second diagram, if White plays 1.Qg8+?, the black king can escape to g6. But White can instead play 1.g6+! first, forcing Black to capture the pawn with 1...Qxg6, blocking the last escape square g6, so that 2.Qg8# is now checkmate.

Examples

Black just got a new queen on e1, and White could do the same. But 1.Ba7+ Kc7 2.b8=Q+ Kxc6 would be an equal endgame. However, White can play 1.c7+! first, forcing Black to block the escape square with 1...Bxc7, and then 2.Ba7# is checkmate.

Sometimes blocking the escape square can be combined with a deflection, as in the next example:

White can win with the deflection 1.Qg8+!.
Black cannot capture with the king, because the knight on h6 is protecting the queen.
Therefore, Black is forced to play 1...Rxg8, blocking the king's last escape square on g8.
The rook is now deflected from guarding f7, and White can win with smothered mate 2.Nf7#.

This combination of a deflection and blocking an escape square is a common way to reach smothered mate.

White can force checkmate with 1.e7+!
If Black replies with 1...Ke8, White can checkmate with 2.Nf6#.
If Black captures either with 1...Bxe7 or 1...Rxe7, blocking the escape square, White can checkmate with 2.Rg8#.
Note how e7 also opened the diagonal b3-g8, so that the checkmating rook is now protected by the bishop.