Explanation

Protecting a square is insufficient, if the protector can be forced away with an attack, leaving the square unprotected.

The following diagram illustrates the most common ways to remove a defender of checkmate:

White is attacking g7 with the battery on the g-file. Capturing with the queen on g7 would be checkmate if the square weren’t defended by the black knight on e6. But Black's defense is not solid, and White can remove the defender in several ways to win material or force checkmate:

• White can capture the defender with 1.Bxe6. If Black recaptures, White can checkmate on the now-unprotected square g7: 1...Bxe6 2.Qxg7#. Black can avoid checkmate with 1...g6, but then White has won the bishop.
• White can attack the defender with 1.f5. If Black runs away with the knight, g7 is unprotected once again: 1...Nf8 2.Qxg7#. Here Black can also avoid checkmate with 1...g6, but then White captures the knight with 2.fxe6.
• The black knight is also protecting the square d8 against a back-rank mate by the white rook on d1. Guarding two checkmate squares, the knight is overloaded and can be deflected with 1.Rd8+! Nxd8 2.Qxg7#. This is even better than capturing or attacking the defender in this case, because checkmate is forced.
• The knight can also be deflected in the other direction: 1.Qxg7+! Nxg7 2.Rd8#.

In this level all puzzles have two moves. The defender that you attack will always be the king itself (otherwise the mate would not be forced, or the puzzle would require more moves).

Examples

Rxh7+ would be mate, but the king protects h7.
White can win by attacking the defender with 1.g5+.
The king is forced to h5, from where it no longer defends h7.
1...Kh5 2.Rxh7# is now checkmate.

Sometimes attacking the defender can guard additional escape squares, for example:

White can win with 1.Nf6+.
The knight cannot be captured because the g-pawn is pinned by the queen.
Black's king is forced to h8, where it no longer defends f8.
1...Kh8 2.Rxf8# is now checkmate, because the knight also guards the escape square h7.

How to Spot an Opportunity to Attack a Defender

When you are threatening checkmate, but the checkmate square is protected, always think about ways to remove the defence.

Related combinations

There are various ways to remove the defence. In addition to capturing the defender, other ways to remove the defence include attacking the defender, and deflection.