Interference means placing a piece on the line between an enemy bishop, rook or queen and the square or piece it defends. The defender has not moved and is not attacked, yet it has stopped defending. Every puzzle on this page involves interference, comes from a real game and is matched to your puzzle rating.
Interference works against line pieces: bishops, rooks and queens, which defend along diagonals, ranks and files. A knight, a pawn or a king defends by a jump or a single step, with no line in between to block, so interference cannot touch them.
The interfering piece is usually sacrificed. That is fine, because the point is not the piece itself but the move or two during which the line stays blocked.
The obvious reply to an interfering piece is to capture it, and if the defender itself can capture, it usually lands back on its line and keeps guarding. That is why good interference moves come with something extra. The interposition can come with check or a bigger threat, so there is no time to capture. Or the piece can land where the lines of two different defenders cross, so that whichever one captures ends up blocking the other.
White: king h2, queen h6, knights e4 and h5, pawns a2, b3, g2, h3. Black: king h8, rook f4, bishop c3, pawns a7, b7, h7. White to move.
White has two mates in mind. Qg7 would be mate, with the queen protected by the knight on h5, but the bishop on c3 guards g7 along the long diagonal. Qf8 would also be mate, but the rook on f4 guards f8 up the f-file. The diagonal and the file cross on f6.
1.Nef6 puts the knight exactly there. If 1...Bxf6, the bishop now blocks its own rook's file and 2.Qf8 is mate. If 1...Rxf6, the rook blocks the bishop's diagonal and 2.Qg7 is mate. Every other black move allows mate next move as well, often 2.Qxh7, since the knight on f6 also covers h7. A sacrifice on the square where a rook's line and a bishop's line cross is known to problem composers as a Novotny.
Trace the lines of the enemy's bishops, rooks and queen to the squares and pieces they guard, especially the squares next to their king. Any empty square on such a line is a place where one of your pieces could cut it. Then ask whether you can land there with a check, a capture or a threat that leaves no time to deal with the intruder.
A useful prompt: when a mate or a win of material fails because of one long-range defender, do not only ask how to remove it. Ask how to get in its way.
The first is interposing a piece that the defender simply takes, landing back on the same line. The second is forgetting a second defender that covers the key square by another route. The third is cutting a line with no threat attached, which gives the opponent a free move to reroute the defender.
Interference is one of the rarer tactics, and it hardly ever appears in the easiest puzzles, so this page suits players who already find pins and skewers comfortably. Before moving, name the defender whose line you are cutting and the square it can no longer reach. If you are stuck, the first hint shows which piece to move, then the move; the full line appears beside the board after you solve. Interference sits close to deflection: one moves the defender off its post, the other blocks its line.
For mixed tactics at your level, use Puzzle Training. For speed, try Puzzle Storm, and to repeat a fixed set until it is automatic, the Woodpecker Method. Elo Maxing rates you on every tactical motif and serves the weakest next, and Pattern Drill builds practice from the patterns your own games show you miss. For a way to find moves like this at the board, read how to find the best move in chess.
Placing a piece between an enemy bishop, rook or queen and the square or piece it defends, so that the defence is cut off.
Only bishops, rooks and queens, because they defend along lines. Knights, pawns and kings cannot be blocked this way.
Sometimes you can, but good interference comes with check or a bigger threat, or lands where capturing it blocks another defender.
A sacrifice on the square where an enemy rook's line and an enemy bishop's line cross, so that whichever of them captures blocks the other.