The bishop against the rook pawn — one square on its path is enough

Draw White to move · Minor-piece endgames · Difficulty about Elo 1300

The plan

A bishop holds up a single passed pawn without its king even needing to be nearby — it only has to control ONE square on the pawn's path. The bishop's colour does not matter here: the queening square is dark, the bishop is light-squared, and it still holds, because the square IN FRONT of it is light. More important than colour is timing. In this position that only works with a single move, namely the one into the corner: all the other squares on the same diagonal do see the same square, but they stand within the black king's reach. After that the task is done — the white king strolls across at its leisure, and the moment the pawn moves it is captured. If it were just one square further forward, the position would be lost: then there would be no square left that a light-squared bishop could reach.

Rule of thumb: a bishop stops any single pawn as long as it sees one square on its path — look for that square, not the bishop's colour.

Why this level: One square on the path is enough for the bishop

The solution, move by move

1. 1. Bb1 The ONLY move that holds, out of twelve. The bishop guards the square in front of the pawn; the queening square itself is dark and out of its reach. The bishop sees the same square from the other corner too — but there the black king picks it off (first sideline). And whoever leaves the diagonal entirely watches the pawn run through (second sideline).
   Sideline 1. Bg8 The same square, the same diagonal — just from the other side. And promptly a serious mistake. 1… Kxg8 The king simply captures the bishop. A blocking square is no use when the piece guarding it stands within reach. 2. Kf2 a2 3. Ke3 a1=Q The pawn promotes. A safe half point has become a lost game.
   Sideline 1. Be4 The bishop stays on its diagonal and looks safe — except it no longer sees the decisive square. 1… a2 The only winning move, and it is obvious: the pawn steps onto the square nobody is guarding right now. 2. Bb1 One move too late. Now the bishop does stand on the right square, 2… axb1=Q+ but the pawn captures it and queens in doing so. Exactly one tempo separates a draw from a loss here.
2. 1… Kg7
3. 2. Kf2 From here there is nothing left to do. The king marches off, more out of tidiness than necessity — the bishop alone already holds the position.
4. 2… Kf6
5. 3. Ke3
6. 3… Ke5
7. 4. Kd3
8. 4… Kd5
9. 5. Kc3
10. 5… Kc5
11. 6. Kb3 Now the king attacks the pawn too. Black has only the advance left, otherwise the pawn falls without a fight.
12. 6… a2 The pawn steps onto exactly the square the bishop has been guarding the whole time.
13. 7. Bxa2 And is captured. King and bishop against the bare king — a draw, there is no mate.

More in Minor-piece endgames

• The wrong bishop — the corner has not been reached yet White wins
• The bishop against two connected passed pawns Draw
• The knight holds up the rook pawn Draw
• The knight against two connected passed pawns Draw
• Opposite-coloured bishops — the blockade Draw
• Knight and rook pawn — the pawn must not go to a7 White wins