Knight and Bishop Checkmate
King, bishop, and knight against a lone king is a win — but it's widely considered the hardest of the four basic checkmates to actually execute, and the reason has nothing to do with the material being weaker. It's that the mate only works in ONE specific corner, and getting the enemy king there without any exact memorized moves takes real, patient technique.
Only one corner works
A bishop only ever controls squares of its own color, and a knight can't make up the difference the way a second bishop would — so this mate only works in the corner that matches the bishop's square color. Drive the king to the wrong corner and it's a permanent draw, no matter how much time is left on the clock or how careful the technique otherwise is.
Starting position. Knight and bishop checkmate — the right-colored corner.
The king is being herded specifically toward the corner that matches the bishop's color — the other corner would be a dead end for the attacking side, not the defender.
The 'W' maneuver
Because the knight and bishop have to coordinate precisely rather than simply boxing the king the way a queen does, the standard method for herding the king toward the correct corner is often described by the zigzag path the attacking king walks — commonly called the 'W' maneuver, for the rough shape it traces across the board as knight, bishop, and king slowly close the net.
Why this is genuinely the hard one
The queen boxes a king in with one piece controlling two directions at once. Two bishops cover both colors between them. This mate has neither luxury — the bishop only ever half-covers the board, and the knight's short, awkward hops mean it often needs several moves just to reposition to a square that's actually useful, all while the king could otherwise be escaping toward the wrong-colored corner if it isn't herded carefully.
Historically the endgame with the most patience built in
Older tournament rules sometimes allowed extra moves specifically for this checkmate because it takes so long to force correctly — modern rules no longer give any special allowance, but the fact that the exception existed at all says something about how much harder this mate is than the other three basic ones.
If the king is already in the wrong corner
The technique starts by identifying which corner actually matches the bishop's color, then herding the king AWAY from the wrong corner and toward the right one, using the knight and king together to cut off retreat squares, before the final squeeze even begins — trying to finish the mate while the king still sits in the wrong corner throws the whole endgame away as a draw.
Why it's worth learning anyway
This exact material imbalance doesn't come up often in real games — most games with an extra minor piece also have other material on the board, or the losing side resigns long before it's reduced to a bare king. But the underlying skill it teaches, coordinating two pieces that each cover the board incompletely to compensate for each other, shows up constantly in messier middlegame and endgame positions where nothing is nearly this clean.
For the easier, either-corner version of this same rough idea, see two bishops checkmate, where a second bishop covers the color this endgame's knight can't.
Frequently Asked Questions
How do I know which corner is the right one before I start?
Check the color of the square your bishop is on — a light-squared bishop mates in a light corner (a8 or h1), a dark-squared bishop mates in a dark corner (a1 or h8). It's worth checking this before committing to a direction, since herding the king the wrong way wastes real moves.
Is there really no way to mate in the wrong-colored corner?
Correct — it's a structural fact, not a difficulty issue. A bishop can never influence a square of the opposite color no matter how the pieces are arranged, so the wrong corner is a permanent, unbreakable draw with this exact material.
Why does this endgame take so many more moves than king and queen vs king?
Because the knight has to spend extra moves getting to squares that are actually useful — it can't simply glide there the way a bishop or queen can — and because the whole plan first requires herding the king toward a specific corner rather than just any edge of the board.