How to Checkmate a Bishop King in Gangster King
· Gangster King
To checkmate a bishop king, give check with a piece it cannot capture and make sure its diagonals are blocked or covered. A bishop king moves only along diagonals, so it has no sideways or straight moves at all. Two pawns in the right place can shut it in completely, and in the corner a single protected piece can be enough.
This guide is for the days when the kings move like bishops. If you are new to the variant, read how to play Gangster King first, then try what you learn in a free game on the Gangster King page.
How a bishop king moves
A bishop king slides any number of squares along a diagonal, and stops when it meets a piece. It may capture an enemy piece that is not protected, and it may not move onto a square the enemy attacks. It can never step one square up, down or sideways.
From e4 the bishop king has up to thirteen squares along its four diagonals. In the open it is hard to trap. From e4 this king can go to a8, b1, b7, c2, c6, d3, d5, f3, f5, g2, g6, h1, h7.
In a corner it has a single diagonal, here the long one from a1 to h8. That is where it is weakest. From a1 this king can go to b2, c3, d4, e5, f6, g7, h8.
The king never changes colour
A bishop stays on one colour of square, and so does a bishop king. At the start the white king stands on e1, a dark square, and the black king on e8, a light square. So the white king lives on dark squares for the whole game, and the black king on light squares. Two facts follow.
- Only some of the enemy bishops can ever check the king. White's light-squared bishop can attack the black king, but White's dark-squared bishop never can, because the black king never stands on a dark square. Keep the right bishop and trade the other.
- The kings never bother each other. An enemy bishop king attacks only squares of its own colour, and your king is always on the other colour. Neither king can take squares away from the other, and there is no opposition as in king and pawn endings.
Two pawns can lock the king in
In ordinary chess a king on g8 has three neighbouring squares to run to. A bishop king on g8 has only two ways out, f7 and h7, both diagonals. If its own pawns stand on f7 and h7, it cannot move at all. Then a rook on the back rank is checkmate.
Checkmate. The rook on a8 checks along the eighth rank. The bishop king's only moves would be to f7 and h7, and its own pawns are there. With an ordinary king this position is not mate, because the king could step to g7.
This is the bishop king's version of the back-rank mate, and it needs one pawn fewer than usual. A pawn on g7 is not needed to lock the king in. In fact it is better to keep it, as the next example shows.
A smothered mate with a knight
The same locked king can be mated by a knight. A knight cannot be blocked, and it does not need the king to be hemmed in on a rank. With pawns on f7 and h7 and nothing on g7, a knight on f6 gives check and nobody can take it.
Checkmate. The knight on f6 checks the king on g8. The king cannot move, and neither the f7 nor the h7 pawn can capture on f6.
Now put a pawn back on g7. It guards f6 and h6, so the knight can simply be taken.
Not mate. The g7 pawn captures the knight: gxf6. The pawn in front of the king is the best defence against a check by a knight.
So when you defend, do not move the g-pawn lightly. When you attack, look for a knight check on a king whose diagonals are filled with its own pieces.
The corner and the long diagonal
A bishop king in a corner has one diagonal, and a check along it is hard to answer. The king can only slide along that same diagonal, where the checking piece is attacking every square. If the checking piece is protected, the king cannot capture it either. Black's king can stand on a8 or h1, and White's on a1 or h8.
Checkmate. The queen on d5 checks the king on a8 along the long diagonal. The king could only go to b7, c6 or capture on d5, but the queen covers b7 and c6 and the pawn on e4 protects the queen.
In ordinary chess the king on a8 could step to a7 or b8 and there would be no mate. Here those squares are not reachable. The lesson for the attacker: when the king is on an edge, attack its one diagonal and protect the checking piece. The lesson for the defender: do not walk the king into a corner if you can avoid it.
Watch out for stalemate
A king with so few moves is easy to stalemate. If every other piece you own is blocked, a king boxed in by its own pawns has no legal move, and the game is drawn the moment you take away its last pawn move with a quiet move.
Stalemate, with Black to move. The king is shut in by its own pawns on f7 and h7, and both pawns are blocked by the white pawns in front of them. Black is not in check and has no legal move.
Before you play a move that wins material when you are already ahead, count your opponent's legal moves. If a locked king is all they have left, give it a diagonal to breathe on, or give check instead.
A plan for mating a bishop king
- Find its colour. The white king is on dark squares and the black king on light squares. Only your bishop of the right colour attacks it.
- Shut the diagonals. Pieces on the king's diagonals, its own or yours, take away its moves. A king boxed in by its own pawns is a liability.
- Check with a piece it cannot take. Protect the checking piece, or use a knight, which stays out of the king's lines.
- Check for stalemate before you take the last free move away.
The bishop king rewards patience: it is slow to escape from a box, but fast to run away from one in the open. Keep your pieces active, open the diagonals your own king needs, and look at its position again after every move. For the other kings, see how to checkmate a knight king, and sharpen your tactics with the puzzles.