The Philidor position
The rook on b7 is guarded by its king and blocks the queen's checks. If it were Black to move, every move would lose: the rook would have to leave its king, and the queen would then win it with forking checks or mate. A position where the side to move must make a damaging move is called zugzwang.
The position carries the name of Philidor, who analysed it in the eighteenth century.
Losing a tempo
With White to move, the queen makes a triangle to pass the move to Black: Qe5+ Ka8, Qa1+ Kb8, Qa5. The pieces stand where they began, but now Black is to move.
The rook's toughest try is to run far away, as with Rb1. Then a series of checks wins it: Qd8+ Ka7, Qd4+ Ka8, Qh8+ Ka7, and Qh7+ attacks the king and the rook on b1 at once.
Typical mistakes
Natural moves can throw the win away. From the start, Qb5, Qc5 and Qb6 only draw, and Qc3 walks into Rc7+, which skewers the king on c6 and the queen behind it.
Keep your king close to the defending king, and before every move look for rook checks that skewer, and for rook sacrifices that leave the defending king stalemated.
Remember
- Recognise the zugzwang
- Triangulate with the queen to lose a tempo
- Win the rook with forks and skewers
- Watch for stalemate tricks