Opening principles and typical mistakes

A game on lichess.org, 2014. White opened with the King's Gambit: 1. e4 e5 2. f4. Black declined the pawn and developed the bishop, 2… Bc5. White took on e5 anyway: 3. fxe5. A pawn is won, but there has been no pawn on f2 in front of the king since move two, and the knight on g1 never went to f3. Black to move.

White won a pawn and lost a rook. The move 2. f4 opened the diagonal to the king, but it could have been closed with 3. Nf3: the knight covers h4. The capture on e5 spent that move on a pawn. Almost every opening disaster looks like this: one move breaks a principle, and the opponent uses it at once. In chapter 10 you learned the principles themselves. This chapter is about what happens when they are broken, and how to punish it.

The three tasks of the opening

The opening has three tasks. Put pawns in the centre or control it with pieces. Bring out the minor pieces, that is, complete your development. Tuck the king away by castling. Everything else, from opening names to long variations, is a way to solve these three tasks faster than the opponent.

"Faster" is the key word here. A move that brings a task closer to completion is said to gain a tempo. A move that achieves nothing loses one. At the start of the game a tempo is expensive. If you spend two moves on what the opponent did in one, their pieces come out sooner, and they are the one who gets threats. Experienced players say that three tempi in the opening are worth about a pawn. It is a rough estimate, but it explains why gambits exist at all: a player gives up a pawn to gain time.

Tempi are lost in different ways. The same piece moves twice for no reason. A piece goes to a square from which an enemy pawn chases it, and it has to move again. A pawn makes a move that helps neither the centre nor development. The queen wanders around the board while the opponent develops pieces by attacking it.

There is a simple way to count tempi. Take the position after a few moves and give each side one point for every developed minor piece, every pawn in the centre and for castling. A piece that stands on a bad square or is about to be chased away counts as half. If one side has two or three points more, it is ahead in development and should act before the opponent catches up.

Needless pawn moves

Every pawn move does two things. It gives something: space in the centre, a line for a bishop. And it takes something away: squares the pawn no longer protects and lines it no longer closes. Pawns do not move backwards, so the weakening stays for good.

The most dangerous are pawn moves in front of the king. The f2 pawn closes the e1–h4 diagonal, the f7 pawn the e8–h5 diagonal. You saw this in Fool's mate and at the start of this chapter. Moves with the edge pawns, a3, h3, b4, usually just lose a tempo in the opening, and sometimes open a line to a rook still sitting in the corner.

Notice that b4 on its own did not hang anything. The rook on a1 was where it always is, and the queen on d5 was not looking at it. The mistake showed only in combination with something else, the open e-file. That is often how it goes. A pawn move creates a weakness, and the punishment comes when the opponent has a piece that can reach it.

This does not mean that flank pawn moves are always bad. In queen's pawn openings c4 fights for the centre. g3 before putting the bishop on g2 weakens f3 and h3, but the bishop covers them. Such moves are made for a specific purpose, on the understanding that the weakened squares will be protected. A bad pawn move is one with no purpose: h3 "just in case", or a3 to stop an enemy bishop from ever coming to b4 when the bishop had no plans to go there.

The early queen

The queen is the strongest piece, and that is exactly why it is vulnerable in the opening. It cannot be left en prise, and every enemy minor piece that attacks it gains a tempo: the piece develops and the queen moves away. Worse, the queen can be pinned. If there are no friendly pieces between the queen and the king, an enemy bishop steps onto that line, and the queen can no longer leave.

Black makes the same mistake too. In the Scandinavian Defence the queen comes out to d5 early and, once a knight attacks it, looks for a square to go to. One of the squares looks natural but puts the queen on the same line as the king.

An early queen is not always a mistake. In the Scandinavian Defence the queen comes out on move two, and it is a normal opening. But then every queen move has to be checked: which square it goes to, who can attack it there, and whether it ends up on the same line as the king.

A special case is a queen that comes out early with a capture. In the Centre Game 3. Qxd4 wins the pawn back, and without it White would be a pawn down. The queen capture is justified, but it hands the opponent a tempo: Black develops the knight with an attack. White should decide in advance where the queen will retreat and choose a square where it cannot be pinned or chased again.

Greed

An extra pawn in the opening looks tempting. Sometimes you really can take it. But for every pawn the opponent gets time, and if the capture is made with the queen, the queen ends up far from its own pieces, on the edge of the board, where it has few squares. Hence the old rule: before taking a pawn, look at how the queen will get back.

Greed can be deliberate. A gambit is an opening in which one player gives up a pawn on purpose for development and attack, and the opponent then decides whether to take it. Taking the pawn and returning it at a convenient moment is a normal way to play against a gambit. Taking it and hanging on to it at any cost while falling behind in development is the road to defeat. More about gambits in the next chapter.

Greed comes in another form as well. A player sees that they can win a piece and does not check what the opponent will reply. That is the subject of the next part of the chapter.

The king in the centre

While the king stands on e1 or e8, the central files are dangerous for it. Open the d- or e-file, and an enemy rook or queen lines up right opposite the king. So in openings where the central pawns get traded quickly, castling becomes urgent. If the centre is closed by pawns, the king can stay in the middle longer: the lines to it are shut, and the opponent will not open them soon. But even then, watch that you do not lose the right to castle, for example by moving the king to get out of a check. One of the most famous short games in chess history is about exactly this.

Now Black has a temptation. The knight on f6 can take the knight on e4, and it looks like simply winning a piece: the e4 knight is defended only by the queen on d3. Let us see what the engine thinks of it.

This game gathers almost every mistake of the chapter. An early queen on both sides, but White managed to castle and put a rook on the d-file, while Black spent moves on the queen and a pawn. An open centre with the king on e8. And at the end, greed: a piece taken without checking the opponent's reply. Qd8+ is exactly the combination from the previous chapter, a forced chain with a sacrifice.

Notice the choice of castling too. Réti castled long. Long castling puts the rook on the d-file at once, and in positions with an open centre this is often handier than short castling: the rook joins the game without an extra move. On the other hand, the king on c1 stands further from the corner and is usually less sheltered than on g1. How to choose the side for castling is something we will cover in the strategy part.

Opening traps

An opening trap is a position where a natural-looking move loses. Many traps have names, generations of players know them, and people still fall into them every day. Usually the victim of a trap takes something that looks free.

Here is one of the best known, in the Queen's Gambit. It is called the Elephant Trap. After 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Bg5 Nbd7 5. cxd5 exd5 White sees that the knight on f6 is pinned by the bishop on g5: if it moves, White takes the queen on d8. It seems that nobody can defend the d5 pawn, and White takes it with the knight, 6. Nxd5.

The pin on the f6 knight was not an absolute one: behind it stood the queen, not the king. Black could break it if they got more than the queen in return. Bb4+ is exactly the in-between move with check that changes everything.

Knowing traps is useful so that you do not fall into them yourself. Setting them in order to win is a poor strategy. A move that counts only on the opponent's mistake is usually worse than a normal one, and against a strong player you will be left with a worse position. A good opening move is useful in its own right and still leaves the opponent a chance to go wrong.

How do you avoid falling into one? The main sign of a trap is a gift. If in a well-known opening the opponent has left a piece or pawn undefended and you can take it at once, stop and ask yourself why nobody defended it. Experienced players rarely give material away for nothing. Look at the opponent's move after the capture: checks, captures, pins, attacks on the queen. If there is nothing dangerous, take it. If there is even one check, calculate it to the end.

A check on every move

All the mistakes in this chapter are alike: the player was thinking about their own plan and did not look at what had changed on the board. Before every move in the opening, ask yourself four questions.

1. What did the opponent's last move change? What does it attack, which lines did it open?
2. Does my move help development, the centre or the king's safety?
3. Which squares and lines does my move open? Does the opponent have a piece that can use them?
4. If I am taking material, what will the opponent answer with a check, a capture or a threat?

These questions take a few seconds, and in quick games they will become a habit over time. Many defeats in the first fifteen moves happen precisely because one of them was not asked.

What's next

The principles explain why each opening move is made. Concrete openings show how strong players solve the three tasks in different positions. The next chapter is about the open games, which begin with 1. e4 e5: the Italian and the Spanish, the Scotch and the gambits.