What is the opposition in chess?

The opposition is when two kings face each other on the same line with one square between them. Because kings can't touch, the side to move must step aside, and the other side is said to have the opposition. In king and pawn endings, the side with the opposition can often push the enemy king back and reach a key square, which decides the game.

How do you win the Lucena position?

In the Lucena position, with the pawn on the seventh rank, your king on the promotion square and the enemy king cut off by a file or more, you win by building a bridge. Lift your rook to the fourth rank, walk your king out, and when the enemy rook keeps checking from behind, bring the king toward your rook and interpose it to block the checks. Then the pawn promotes.

How does the rule of the square work in chess?

Draw a square whose side runs from the passed pawn to its promotion square. If the defending king is inside the square, or can step into it on its move, it catches the pawn. Otherwise the pawn promotes. A pawn on its starting rank can advance two squares, so count it as if it were on the third rank.

Why is a bishop and rook pawn sometimes a draw?

If the bishop doesn't control the promotion square of an a- or h-pawn, it's called the wrong-colored bishop. Once the defending king reaches that corner, it can't be driven out and the game is drawn. For example, an h-pawn promotes on the dark h8 square, so a light-squared bishop can never take control of it.

Chess Endgame Basics: Opposition, Lucena and Philidor

In the endgame, the king becomes a fighter

In the opening and middlegame, the king hides behind its pawns. Once the queens and most pieces are traded, the danger of checkmate drops sharply, and the king turns into a fighting piece roughly as strong as a minor piece. It defends pawns, attacks enemy pawns and escorts its own pawns toward promotion.

So the first thing to do as the endgame begins is bring the king toward the center, where it can reach either wing quickly. Two endgames with equal pawns are often decided by whose king is more active, and a king that arrives one move late can fail to hold even a pawn-up position.

Opposition and key squares in king and pawn endings

Opposition is when the two kings stand on the same line with one square between them. Kings can't touch, so the side to move has to give way. The side that doesn't have to move is said to have the opposition, and it can push the enemy king back and walk into the squares it wants.

In king and pawn versus king, key squares make calculation much easier. For a pawn that isn't on the a- or h-file and stands on the second to fourth rank, the key squares are the three squares two ranks in front of it. For a pawn on e4, they're d6, e6 and f6. Once the pawn reaches the fifth or sixth rank, the three squares one rank ahead and the three squares two ranks ahead are all key squares. If the attacking king reaches a key square, the pawn promotes no matter what the defender does.

Take White's king on e5, a white pawn on e4 and Black's king on e7. With Black to move, the black king must step aside: 1...Kd7 2.Kf6, 1...Kf7 2.Kd6, or 1...Ke8 2.Ke6, and White's king reaches a key square and wins. With White to move in the same position, Black keeps the opposition and draws. One tempo decides everything.

The rule of the square for passed pawns

A passed pawn has no enemy pawns in front of it or on the neighboring files. To know whether a lone king can catch it, use the rule of the square. Draw a square whose side runs from the pawn to its promotion square. If the defending king is inside that square, or can step into it on its move, it catches the pawn.

With a white pawn on a4, the square runs from a4 to e4 to e8 to a8. If Black's king is on f5 and it's Black's move, 1...Ke5 enters the square and the pawn is caught. If it's White's move, 1.a5 shrinks the square to a5, d5, d8 and a8, the king can't get in, and the pawn queens. A pawn still on its starting square can move two squares, so count it as if it were already on the third rank.

Rook endgames: rooks belong behind passed pawns

Rook endgames are the most common endgames in practice. The key principle is to place your rook behind a passed pawn, whether it's your pawn or your opponent's. Behind your own pawn, the rook gains scope as the pawn advances. Behind an enemy pawn, it presses harder the farther the pawn goes.

A rook in front of a passed pawn has the opposite problem: as the pawn advances, the rook runs out of room and ends up tied to passive defense. In general, keep your rook active, cutting off the enemy king or attacking pawns, rather than babysitting.

The Lucena and Philidor positions

The Lucena position is the model win in rook and pawn versus rook. The pawn is on the seventh rank, the stronger side's king sits on the promotion square in front of it, and the defending king is cut off by at least one file. The difficulty is that when the king steps out, the enemy rook checks from behind. The solution is called building a bridge.

Consider White: Kg8, pawn g7, Re1; Black: Kd7, Rh2. Play goes 1.Re4! Rh1 2.Kf7 Rf1+ 3.Kg6 Rg1+ 4.Kf6 Rf1+ 5.Kg5 Rg1+ 6.Rg4. The rook steps between the king and the checking rook, the checks run out, and the pawn promotes. Lifting the rook to the fourth rank in advance is what makes the bridge work.

The Philidor position is the model draw for the defending side. With the defending king on the promotion square, the defender keeps the rook on its own third rank to stop the enemy king from advancing. For example, with Black's king on e8 and rook on b6 against White's king on d5, pawn on e5 and rook on a7, Black simply holds the sixth rank. Once White pushes e6, the white king loses its shelter, so Black drops the rook to the first rank and checks from behind for a draw.

Trading down and the theoretical draws

When you're ahead in material, trade pieces, not pawns. Fewer pieces mean fewer counterattacking chances for your opponent and a bigger relative advantage for you. When you're behind, trade pawns instead: if all the pawns disappear, a single extra minor piece can't force checkmate.

Be careful about trading into a pure king and pawn ending, though. As the opposition example shows, one tempo can flip the result, so calculate to the end with opposition and the rule of the square before you trade the last pieces. Also remember that endings with only opposite-colored bishops are often drawn even with an extra pawn or two.

The classic theoretical draw is the wrong-colored bishop with a rook pawn. If White has an h-pawn and a light-squared bishop, the promotion square h8 is dark, so once Black's king reaches the h8 corner it can't be driven out and the game is drawn. With an a-pawn, a8 is a light square, so the dark-squared bishop is the wrong one. King and rook pawn versus king is usually a draw too if the defending king reaches the corner.

A step-by-step endgame checklist

Most endgame losses come from rushing. When there's no forced win, work through this checklist.

Step 1: count the material and decide whether the position is a theoretical win or draw.
Step 2: bring your king toward the center or the wing where the fight is.
Step 3: check whether you have or can create a passed pawn, and put your rook behind it.
Step 4: before trading into a king and pawn ending, calculate it fully with opposition and the rule of the square.
Step 5: when the enemy king is on the edge or in a corner, make sure your move isn't stalemate.

Common mistakes, and practicing on Playfulo

The most common beginner mistake in the endgame is pushing pawns while the king stays at home; unsupported pawns are easy prey for the enemy king. Other frequent errors include placing the rook in front of a passed pawn, walking the king up without thinking about who has the opposition, and stalemating the opponent while rushing to finish a won game.

Playfulo follows FIDE basics, including draws by stalemate, insufficient material, the 50-move rule and threefold repetition, so you can practice endgames under real rules all the way to the end. Try trading down into pawn endings against the easy AI, then test your rook endgame defense on normal and hard. You can also create a room, send a friend an invite link and take turns playing the same position from both sides.