Nightrider (chess)

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A typical icon of the nightrider.

A nightrider (also known as a knightmare or unicorn, though the latter sometimes also means the bishop–nightrider compound) is a fairy chess piece that can move any number of steps as a knight in the same direction. The nightrider is often represented by a symbol similar to the knight's icon, but altered in a way to indicate the additional straight-line motion.[1] In this article the nightrider is represented with an inverted knight, and notation N (in which case the knight is abbreviated as S for German Springer).

The nightrider was invented by T. R. Dawson in 1925, and is often used in chess problems.


Movement[edit]

The nightrider moves any number of steps as a knight in the same direction. Intervening squares must be vacant. For example, a nightrider on b2 can reach square c4 and forward to d6 and e8, but cannot jump over the f4-pawn to reach h5.

a b c d e f g h
8
Chessboard480.svg
e8 black cross
d6 black cross
a4 black cross
c4 black cross
f4 white pawn
d3 black cross
b2 white upside-down knight
d1 black cross
8
7 7
6 6
5 5
4 4
3 3
2 2
1 1
a b c d e f g h
Nightrider makes any number of knight moves in the same direction.

Examples[edit]

T. R. Dawson
British Chess Magazine (1925)
a b c d e f g h
8
Chessboard480.svg
c7 white king
a6 black king
c6 white upside-down knight
c3 white knight
8
7 7
6 6
5 5
4 4
3 3
2 2
1 1
a b c d e f g h
#5 (Nightrider c6)


The king together with two knights cannot win endgame against a lone king (KSS vs K), but the king together with a knight and a nightrider can win, because the knight cannot win a tempo, but the nightrider can.

Solution: 1. Ne7! Ka7 2. Ng3 Ka8 3. Ne4 Ka7 4. Sb5+ Ka8 5. Nd2#

a b c d e f g h
8
Chessboard480.svg
c6 black rook
d6 black rook
d5 black king
c3 white king
b1 white upside-down knight
e1 white upside-down knight
8
7 7
6 6
5 5
4 4
3 3
2 2
1 1
a b c d e f g h
Mutual discovered perpetual check with nightriders

With nightriders on the board, a mutual discovered perpetual check is possible.

A possible continuation would be: 1. Kd3+ Kc5+ 2. Kc3+ Kd5+ 3. Kd3+ Kc5+, etc.

a b c d e f g h
8
Chessboard480.svg
e7 black pawn
f7 black king
f5 white pawn
d3 white upside-down knight
f1 white rook
g1 white king
8
7 7
6 6
5 5
4 4
3 3
2 2
1 1
a b c d e f g h
After Black moves his pawn to e5, taking it en passant results in triple check.

Nightrider can also participate in triple check.

References[edit]