Rook against pawn: the race

The key idea

The rook holds it back; the king finishes it off. If your king arrives in time, you win. If it doesn't, the rook ends up giving itself up for the pawn: a draw.

Example 1 · The king arrives: rook and king catch the pawn

The black pawn is running and its king escorts it. But the white king is three steps away, and with the rook holding it back from behind, three steps are enough.

1. Rb8 First rule of this endgame: the rook, BEHIND the pawn. From b8 it watches the whole file: the pawn can no longer advance for free, because the rook controls every square it steps on.
2. b3 Black pushes anyway, with its king glued to it for protection. It's its only hope: reach b1 before the white king enters the scene.
3. Kc3 And here the race ends: the white king reaches the key square. Look at what it does to the pawn: b2 is controlled by the king, and the pawn can't advance without falling.
4. Ka2 The black king tries to clear the way for the pawn by defending the queening square from a2.
5. Ra8+ Check from behind. The rook shows off its other virtue: hitting from a distance. The black king has to choose between going back to b1 (blocking its own pawn) or abandoning it.
6. Kb1 Back to b1, covering its own pawn's queening square. Now the pawn can't advance: it's pinned in place by its own king.
7. Kxb3 And the white king just eats it. Rook and king against a lone king: you already learned that mate in its own lesson. The full recipe was: rook behind to hold it back, king that arrives, and the pawn falls on its own.

Example 2 · The king doesn't arrive: the rook alone only draws

Same rook, same pawn — but now the white king is on the other side of the world. Watch what changes: a seventh-rank pawn with its king beside it is worth a whole rook.

1. Rb8 The rook ties down the pawn from behind: as long as the black king is on b1, it covers its own pawn's queening square, and if the pawn queens with the king away, the rook catches it. The problem is that tying down isn't winning.
2. Ka2 The king steps away to let the pawn queen. It threatens b1=Q next move. Now what?
3. Ra8+ The only resource: check. The black king has no choice but to decide — and no decision gives it the win.
4. Kb1 If it goes back to b1, we're back where we were: its king covers the queening square. We could repeat this forever — check, back, check, back. Draw by repetition.
5. Rb8 The rook returns to its post. Here's the full picture of the draw: if the black king steps away, check; if it hides on b1, the pawn doesn't advance. And if the king ever wanders off from the pawn to escape the checks? Then the rook eats it. In every script, a draw.
6. Ka2 Black tries once more…
7. Ra8+ …and gets the same check. Repetition. Half a point each. The entire difference from Example 1 was one thing: there the white king was three steps away; here it's on vacation on g6. When you enter this endgame, count your king's steps BEFORE deciding whether you're playing to win or to save the draw.

Practice

You play White, in the position from the first example. The black pawn is running toward b1 and its king escorts it — but your king arrives in time. Hold it back, catch up, and capture it.

1. Rook behind the pawn: every square of its path is watched. It can no longer advance for free. First rule: place the rook BEHIND the pawn, on its own file, to watch it the whole way.
2. Your king enters the key square: it controls b2 and the pawn is frozen. The race is won. Now it's your king's turn: bring it to the square the pawn needs to step on.
3. Check from a distance. The black king can only go back to b1 — and there it covers its own pawn's queening square. The black king wants to clear the way for the pawn from a2. Punish it: your rook hits from far away.
4. Pawn caught. Rook and king against a lone king: you already know how to finish that off with the box technique. Game won. The pawn is pinned by its own king and your king has it in range. Eat it.

The race, read and won: rook behind, king that arrives, pawn that falls. And if one day your king does NOT arrive, you already know what comes next from the second example: checks and ties until the draw. This endgame only has those two scripts — now you know both.