In one of the previous lessons 4 possibilities to eliminate the defender have been shown:

• Capturing
• Attacking
• Interference
• Distracting

This chess lesson will be focussed on Interference, also known as blocking the defender. The general idea is to block the line between the defender and the piece or square it is trying to defend.

		An illustrative example of this tactical motif is shown in the diagram on the left. The white Rook is attacking the black Knight, but this Knight is defended by the black Rook. By playing 1.d4+ the protection is removed and the Knight can be captured 2.Rxh4. Please note that it is only possible to block a horizontal, vertical, or diagonal line. It will be impossible to block a defending Knight, pawn or King.
		Let’s have a look at the next diagram. It’s Black’s turn to move. No pieces are attacked, but White’s Queen is an important defender. Without this Queen it was a mate in one. Black can block this defender by 1. …Ra5+, and White has to play 2. Qxa5 to prevent the mate, but also makes that his Queen will be captured 2…bxa5. The mate can not be avoided 3. Kb1 Bg6+ 4. Rc2 Qf1+ 5. Ka2 Bxc2 6. Be1 Qxe1 7. d5 Qb1+ 8. Ka3 Qa1#. A nice example of interference, showing that we have to consider more targets than the attacked pieces.
		This third diagram gives another example. It is White’s turn to move. White has a kind of double attack by means of a queen fork, but each of the rooks is defending the other one. The move 1. d6 blocks this line and Black will be unable to bring both rooks to safety at the same time. Black’s best move is probably 1…Raxd6, but then White will continue with 2.exd6. This example illustrates that it is not necessary for the inferfering piece to attack anything at all.
		I will leave the solution of this last exercise to you. It is White’s turn to move. You are invited to add the solution to the comments. To give a clue: It is a combination of a discovered attack and interference.

The next lesson is a nice example game of interfering: Tarrasch - Allies (1914).

Original 6 Responses on CTL to “Interfering”

1. 
   genius
   November 12th, 2007 at 12:58 am
   1. Bh7 Qxe2
   2. Bxh6++
2. 
   Chess Teacher
   November 13th, 2007 at 6:47 pm
   @genius
   OK, but I don’t think that Black is going to play 1…Qxe2, but probably 1…Rxh7
3. 
   Azizul
   February 15th, 2009 at 9:37 pm
   It is obvious! 1.Nxf7 and White wins.
4. 
   Chess Teacher
   February 16th, 2009 at 6:27 pm
   @Azizul
   Sorry, but it isn’t that obvious
   1.Nxf7 gives away the advantage
   it will probably be followed by 1…d3 2.Qxd3 Kxf7
   You have to look for a combination of a discovered attack and interference to find the right move.
5. 
   JUAN MAREGO
   March 6th, 2010 at 2:34 am
   1. Bh7 Rxh7,2. Qxb2
   (1. ..Qxe2,2. Bxh6++
6. 
   Chess Teacher
   March 6th, 2010 at 10:26 am
   Yes