Potential Barriers

Pieces cannot simply jump through each other if both are active pieces, unless they are knights.

If one piece tries to move to a destination but the opponent moves inside that piece's path (but does not land at the destination) then the piece lands just short of the opponent's destination. This is called a potential barrier.

In this example, black's bishop on f8 will move to h6. Try to capture the h7 pawn with your rook.

Your rook still moved but was blocked and fell just short of black's position.

Two other cases need to be looked at.

• When both pieces are trying to move through each other.
• When one piece blocks another from moving at all.

When the first happens, the piece that moves first takes priority and lands at their destination. The other piece is then blocked by the first.

The second case occurs when one piece moves right up to the other moving piece.

The black rook on a8 hasn't yet moved to a5. Try moving your a1 rook to a7.

As you will see black will be blocked and will not move at all. If black's rook moved first then it would land at a5 and white's rook would be blocked and be placed at a4.

Pieces cannot move through each other's initial positions, or end positions (unless they use the same path and have priority) but they can move past each other's paths if the direction is not shared.

If one rook was moving horizontally and another vertically then there is no interaction. Move the g4 rook to b4 and see that the e6 rook is uninterrupted.