The passed pawn

A game on lichess.org, 2014. A white pawn stands on e7, one step from promotion. The black rook on e5 holds it: it covers e8 along the file. The black king stands on g5, on the same fifth rank as the rook. White to move.

White gave up a rook, and the pawn became a queen. A passed pawn on the seventh rank is so strong that pieces are sacrificed for it. Remember the trick itself as well: pinning a rook to its king for the sake of a pawn comes up all the time in rook endings. In this chapter we look at where passed pawns come from, how to push them and how to fight them.

What a passed pawn is

A passed pawn is a pawn with no enemy pawns in front of it, on its own file or the neighbouring ones. No pawn can stop it or capture it on the way. Only pieces can stop a passer, and a piece that guards a pawn does nothing else.

So a passed pawn grows stronger the fewer pieces there are on the board. In the middlegame it can often be blockaded. In the endgame, especially a pawn ending, a passed pawn often decides the game on its own. The engine in the chapter on evaluation knows this: it values a passed pawn more the further it has advanced, and more in the endgame than in the middlegame.

Aron Nimzowitsch compared a passed pawn to a criminal who must be kept under lock and key. The comparison is apt: a passer is dangerous while it is free and almost harmless with a piece in front of it. So the fight around a passer is always for the square in front of it. One side wants to push it, the other wants to put a piece in its way and keep it there.

Where do passers come from? Most often from exchanges. A pawn captures a piece or a pawn and moves to the next file, the opponent's pawns are traded in the centre, and suddenly one side has a pawn with no opponent ahead. An extra pawn in the endgame almost always becomes a passer sooner or later. So when you calculate exchanges, also look at who will get a passed pawn after them.

Watch how its value changes. On the board below White has an extra pawn on b3, a passer. Push it and make Black's moves. Try two paths: the first time, bring the black king towards the pawn; the second time, move Black's h-pawns. Watch the “Passed pawn” row: once the king can no longer reach the pawn, its value jumps from half a pawn to three.

The rule of the square

Will the king catch the pawn? You do not have to count moves: there is the rule of the square. Picture a square with one side running from the pawn to the promotion square, both squares included. If the opponent's king is already inside the square, or can step into it when it is its turn to move, it catches the pawn. If not, the pawn goes through.

For a pawn on c5 the side of the square is c5, c6, c7, c8. The square covers the files c to f and the fifth to eighth ranks. One correction: a pawn on its starting square can move two squares at once, so its square is built as if it already stood on the third rank.

The rule of the square works in a pure pawn ending, when nothing stands in the king's way. If your own pawns block the path or the opponent can distract the king, you still have to count. But in most cases the square answers the question in a second. It works in defence too: before you take your king to the other side of the board, check that it does not leave the square of an enemy pawn.

The square is easy to see on the board: run your eye along the diagonal from the pawn to the last rank. It cuts off a corner of the board, and that corner together with the squares up to the pawn is the square. If the opponent's king is on the far side of the diagonal and it is not its move, there is no need to count further: the pawn goes through, and you can calmly think about what your own king should do.

How to create a passer

A passed pawn comes from a pawn majority. If you have three pawns against two on a wing, one of them can become a passer. Start with the right pawn: the candidate pawn, the one with no enemy pawn on its file. The other pawns follow it and trade themselves for the opponent's pawns to clear its road.

A majority is pushed together, without haste. Pawns that walk side by side protect each other, and the opponent's king cannot attack them one by one. If one pawn runs ahead, it gets stopped, and the rest lose their support. It helps when your own king walks behind the pawns: it protects them and helps them past the squares the opponent's king controls.

Sometimes a passer is created by force, by sacrificing pawns. This is a breakthrough. The classic position: three pawns against three, standing face to face, the kings far away. Whoever moves first wins.

The breakthrough is one of the most beautiful tricks in the endgame. It is worth remembering, because the same idea works in more complex positions: the opponent's pawns are busy capturing, and one of yours slips through to promote. Before a breakthrough, check two things: whether the opponent's king can reach the new passer, and whether the opponent's own pawns promote while yours are busy breaking through.

Which passers are stronger

A protected passed pawn is a passer protected by a pawn of its own. The opponent's king cannot take it and has to guard it. In a pawn ending this is almost always a win: the king guards the passer, and meanwhile your king collects the pawns on the other wing.

An outside passed pawn is a passer far from the other pawns, usually on a wing. Its strength is that it draws the opponent's king away. While the king goes to catch the pawn, your king comes to the pawns on the other wing and collects them. The board with the “Passed pawn” row at the start of the chapter is just such a case.

An edge passer, on the a- or h-file, has a peculiarity of its own. It is the furthest from the centre and the best at drawing the king away. But in some endings it is worse than the rest: an opponent's king that gets into the corner in front of it often holds a draw, because the pawn cannot be bypassed from the side.

Two connected passers — pawns on neighbouring files, both passed — are stronger still. They protect each other, and if both have reached the sixth rank, a rook alone usually cannot stop them. The opponent's king is helpless against them: taking one lets the other through.

A passer can be strong in the middlegame too. A protected passer in the centre, for example on d5 or d6, cuts the opponent's position in two: their pieces cannot cross from wing to wing, and one of them has to guard the pawn all the time. When the pieces come off, such a pawn usually decides. So strong players are glad to trade pieces in the middlegame when they have a passer, and avoid trades when the opponent has one.

How to push a passer

The rule: passed pawns must be pushed. A pawn on the fourth rank bothers the opponent little, on the sixth it already ties down their pieces, and on the seventh a rook is given up for it. But push the pawn with support. A king in front of the pawn is the best helper in a pawn ending. A rook behind the pawn is the best helper in a rook ending: it supports the pawn all the way, and the opponent's rook in front of the pawn loses room with every step.

This rule is linked with the name of Siegbert Tarrasch: rooks belong behind passed pawns, your own and the opponent's. Behind your own passer, the rook pushes it forward and grows more active with every move. Behind the opponent's, it guards the pawn and also stays active. A rook in front of the pawn, on the contrary, is squeezed tighter with each of its steps.

In a pawn ending the king escorts the pawn from in front of it: it occupies the squares the pawn will pass through and keeps the opponent's king away from them. A king behind the pawn helps much less. Exactly how the king escorts the pawn, and where the opposition comes in, we look at in the chapter on pawn endings.

A pawn on the seventh rank often gives tactics. If only one enemy piece holds the promotion square, that piece can be deflected: with a sacrifice, a check, a pin. That is what happened in the position at the start of the chapter. Here is one more example.

Here is an example where the passer goes through without sacrifices: the opponent's piece simply does not get there in time.

Pawn races

When both sides have passers, a race begins, the sharpest situation in the endgame: here one tempo decides the game. Count who queens first, and look at the details: whether the new queen comes with check, whether it can stop the opponent's pawn at once. A queen that appears one move earlier often catches the opponent's pawn or wins their new queen.

In a race, count the moves exactly: one pawn may move two squares from its starting square, another may promote with check. Take into account where the new queen will stand as well. A queen against a pawn on the seventh rank usually wins, but against an edge pawn or a bishop's pawn supported by its king it can be a draw: the king hides in the corner, and taking the pawn gives stalemate.

How to stop the opponent's passer

The main weapon against a passer is the blockade: put a piece directly in front of the pawn. Aron Nimzowitsch wrote that a passer must be blockaded: a pawn that is stopped loses its force, and the pawn cannot threaten the blockading piece in any way. The best blockader is the knight: even from the blockading square it hits squares in every direction. The queen blockades worst of all: the strongest piece spends its strength on a pawn.

In the endgame the best blockader is the king. It stands in front of the pawn, and the pawn does not get through as long as the opponent has no help. In a rook ending the rook goes behind the opponent's pawn: from there it presses on the pawn and does not get in the way of its own pieces. But remember the square: if the king is too late, there will be nothing to blockade with.

It is better to stop a passer as early as possible. A pawn on the fourth rank ties down one piece, on the sixth already several, and each of its steps costs the opponent a tempo and space. If you see that the opponent is about to get a passer, think whether you can prevent it from appearing: trade off the candidate pawn or occupy the square in front of it in advance.

Remember counterplay as well. While the opponent pushes their passer, look for one of your own: the race is won by whoever counts more precisely, and that is not necessarily the owner of the most advanced pawn. Sometimes the best defence against a passer is to create your own on the other wing and make the opponent get distracted.

What's next

The blockading square in front of a pawn is a special case of a weak square: a square that no pawn can defend. Such squares exist in every position, and a piece that occupies one becomes the strongest on the board. That is the subject of the next chapter.