In this level, your opponent is attacking one of your pieces. You must protect that piece.

To protect a piece means to move another piece into a position where it can recapture if the attacked piece is captured. This is also sometimes called guarding or just defending

Protecting works best if the value of the piece being attacked is lower than or equal to that of the attacking piece; otherwise, protecting the piece will not avoid material losses (although you may still protect the piece to minimize loss, if no better option is available).

In the first diagram, Black’s rook is attacking White’s bishop. The rook can protect the bishop, because Black would now lose the exchange in case of a trade.

In the second diagram, Black’s rook is attacking White’s queen. Protecting the queen with the rook is not an ideal solution, because White would still lose a queen for a rook in the trade.

In the third diagram, Black is attacking White’s bishop with a battery of two rooks, and the bishop is only defended by one rook. White can add an additional defender with the second rook, building their own defensive battery. This is a good defense, because Black would now lose the exchange in case of a trade.

As with blocking, there are several reasons why protecting might be preferred over running away:

• If there is no safe square available
• If the attacked piece is pinned. (Again, this means there is a more valuable piece or the king behind it and therefore it can’t move away.)
• If the attacked piece has an important task that it can’t fulfill if moved away. For example, the attacked piece might be protecting another piece or square.

Examples

Black's bishop on c5 is attacking White's unprotected knight on d4.
Running away with the knight is not possible, as it would leave the white king on g1 in check (the knight is "pinned").
The correct move is 1.c3, protecting the knight on d4. If Black captures with Bxd4, White can now recapture with cxd4.

The white rook on b1 attacks Black's unprotected bishop on a5.
Running away with the bishop allows White to capture the other bishop on b7 with Rxb7.
Therefore, you have to protect your bishop with your pawn and play 1...a5. Now Rxb4 is no longer a good move for white, as it would now lose the exchange (rook for bishop or knight) after axb4.

Advanced question: Could White win one of the bishops now with 2.a3?
Answer: No, Black could defend against that with the counterattack 2...Be4!