Open files and the seventh rank

A game on lichess.org, 2014. The white rook has already come down the open d-file and stands on the seventh rank. In front of it is the black pawn on g7, and beyond it the king on h5, pressed to the edge of the board. White to move.

In one move the rook on the seventh rank took a pawn and set up mate. To get there it needed an open file. In this chapter we look at how rooks seize open files, how to fight for a file the opponent has taken, and what a rook does on the seventh rank.

The open file

An open file is a file with no pawns on it. A rook on it hits the whole file, from its own edge to the opponent's, and can go along it into their camp. If only an enemy pawn is left on the file, the file is half-open: the rook presses on that pawn but cannot get further while the pawn stands.

Rooks are the slowest pieces at the start of the game. Their own pawns are in the way, and until the first exchanges in the centre a rook usually sits in the corner. As soon as pawns are traded, open lines appear and the rooks come to life. So in the middlegame ask yourself: where is the open file, and whose rook will be first on it?

Aron Nimzowitsch wrote that an open file is only a means. The goal is to get along it into the opponent's camp, to the seventh or the eighth rank. A rook that just stands on an open file does not press on the opponent much. Its strength appears when it has an entry square: an unprotected square on the seventh, sixth or eighth rank where it can land.

If there are several open files, choose the one that leads to an entry square. A rook on an open file whose far end is fully guarded just stands there. A rook on a file that runs into an unprotected square on the seventh rank threatens to go in on the very next move. Look also at which file the opponent can contest: if they have a free rook next to one of the files, take the other, where they have nothing to contest it with.

To hold an open file firmly, both rooks are put on it, one behind the other. Such doubled rooks protect each other, and the opponent cannot contest the file with one rook: after an exchange the second one stays on the file. Sometimes the rooks are doubled with the queen as well: the queen in front and the rooks behind, or the other way round. That makes a battery of three pieces.

A half-open file is useful too, only in a different way. A rook on it presses on an enemy pawn, and the opponent has to defend it. A weak pawn is an especially convenient target: an isolated pawn, a backward pawn, a c- or d-pawn after an exchange in the centre. The opponent puts pieces on its defence, they lose their mobility, and meanwhile you prepare a blow elsewhere. Such pawns and how to attack them were covered in the chapter on pawn structure.

The engine values a rook on an open file, and a rook on the seventh rank even more. On the board below the c- and d-files are open. The black rook already stands on c8, the white one is in the corner on a1. Play Rd1, make a quiet move for Black, for example …Kf8, and put the rook on d7. Watch the total evaluation and the rook rows.

At first the evaluation favours Black: their rook is on an open file, the white one sits in the corner. After Rd1 the rooks are equal, and the evaluation is close to zero. On d7 the white rook gets a “Rook on the seventh” row, and the evaluation crosses over to White's side. Not a single pawn has been taken: the advantage came from one rook standing on the right square.

The fight for a file

If the opponent has taken an open file first, do not give it up without a fight. The usual answer is to put your own rook on the same file, opposite theirs. Then the opponent either trades rooks, and the file belongs to nobody, or retreats, and the file passes to you. Only make sure your rook is protected. Otherwise the opponent simply takes it with check, as often happens with a rook on the first rank when the king has no escape square.

When rooks are traded on an open file, watch who recaptures last. The file goes to the side whose piece is left on it after the exchange. If you have another rook or the queen behind your rook, the exchange suits you: afterwards your piece stays on the file. If you have no such piece and the opponent does, the exchange hands them the file.

If you have nothing to contest the file with, close the entry squares. The opponent's rook goes along the file only where it will not be taken. Put pieces on those squares, protect them with pawns, and the rook will stand on the open file with nothing to do. A bishop or a knight that holds an entry square is often worth more than it seems: trade it off, and the opponent's rook gets in at once.

An open file can also be created. To do so, a pawn is traded for an enemy pawn: for example, after the exchange cxd5 White no longer has a c-pawn, and the c-file becomes half-open or open for their rooks. Before starting such an exchange, check who will be first to put a rook there. If the opponent's rooks are closer, you will open the file for them.

The seventh rank

The seventh rank is the opponent's second rank, counting from their edge. For White it is the seventh rank, for Black the second. A rook on the seventh does two things at once. It attacks the pawns that still stand on their starting squares, and they are awkward to defend from behind. And it shuts the opponent's king in on the last rank, where it cannot come to help.

The engine gives less than a pawn for a rook on the seventh. But in a real game it often wins a pawn, or even two, so a pawn is often given up to get onto the seventh, and nobody regrets it. In the endgame a rook on the seventh against an enemy rook tied to the defence of pawns often decides the game by itself.

A rook on the seventh is especially strong when the opponent's king stands on the last rank. Such a position is called the absolute seventh: the king cannot step forward, the rook holds it like bars, and any second piece nearby threatens mate. If the opponent's king has already left the last rank, the rook on the seventh only attacks pawns, and its strength is smaller.

A rook often enters the seventh with check. If besides the king there is another enemy piece on the seventh, the check turns into a fork. Find such a move in two games.

A rook on the seventh is stronger still together with a bishop aimed at the opponent's corner. The rook gives check, steps away with a discovered check from the bishop and comes back again. This trick is called a windmill: with every turn the rook collects a piece or a pawn.

Two rooks on the seventh are even more dangerous than one. They protect each other, take the pawns one by one and often mate a king shut in on the last rank. English books call them pigs on the seventh: they eat everything that stands on the rank. Against two rooks on the seventh the defending side is usually glad of a perpetual check.

Defending against a rook on the seventh is hard, but possible. The king goes towards it and takes squares away from it, a rook from the last rank comes up to the seventh itself and offers an exchange, and the pawns the rook attacks are sometimes better pushed, so that they leave the rank. The main thing is not to let the rook in: if the entry square can be closed in advance, close it while the rook is still on the open file.

The seventh rank in the endgame

In the endgame a rook on the seventh is strong in its own way. It cuts the opponent's king off on the edge of the board, and the king cannot come to its pawns. And their pawns on their starting squares have nothing to defend them from behind. Look at this position from Black's side: Black's rook is already on White's second rank, and the white rook attacks the knight.

If your rook has left the seventh, getting it back there can be hard: the opponent will have time to cover the entry. So once your rook is on the seventh, take it away only for a serious reason.

In a rook ending the activity of the rook often matters more than a pawn. A rook that stands on the seventh or attacks pawns from behind keeps the opponent under strain. A rook that passively defends its own pawn is tied down and does nothing. So experienced players in rook endings are glad to give up a pawn if the rook becomes active in return. More on this in the chapter on rook endings.

Open diagonals

Lines can be diagonal too. An open diagonal is a road for the bishop and the queen. A bishop on the long diagonal a1–h8 or h1–a8 hits squares from corner to corner and often looks straight at the opponent's king. If its own pawn stands in front of it, its strength is hidden, but once the pawn moves away, the diagonal opens.

The best-known way to put a bishop on a long diagonal is the fianchetto: the g- or b-pawn takes one step forward, and the bishop goes to g2 or b2, to g7 or b7. Such a bishop presses on the centre and on the opponent's queenside across the whole board. While pawns stand on the diagonal, it waits; after an exchange in the centre it often becomes the strongest piece.

A queen and a bishop on one diagonal form a battery. The queen in front, the bishop behind, and a blow on the square in front of the king, for example h7 or g7, becomes deadly. Against such batteries it is better to close the diagonal with a pawn or a piece before the opponent builds it.

The fight for open diagonals is like the fight for files. Whoever puts a bishop there first does the pressing. If the opponent's bishop holds the diagonal, put yours opposite it and offer an exchange. And if you have no bishop of that colour, close the diagonal with a pawn: pawns only move forward, so this decision is for a long time, but the opponent's bishop will become much weaker.

Let us sum up with three questions worth asking yourself in every position. Where are the open and half-open lines? Whose piece will be first on them? And where will that piece go in next — is there an entry square on the seventh or eighth rank? If the answer to the third question is “nowhere”, the open line gives nothing yet, and the rook is better placed where it will be more useful.

What's next

A bishop loves open diagonals, a knight loves firm squares. Which of them is stronger depends on the pawns: in an open position the bishop more often wins, in a closed one the knight. That is the subject of the next chapter.