Nightrider (chess)

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Nightrider makes any number of knight moves in the same direction.

A nightrider (also known as a knightmare or unicorn) is a fairy chess piece that can move any number of steps in a direction that a knight can move. For example, a nightrider on b2 can reach square c4 and forward to d6 and e8, but cannot jump over pawn f4 to h5. The nightrider is usually represented by an inverted knight on diagram and symbol N in text, in which case the knight is abbreviated as S for German Springer. Nightrider was invented by T. R. Dawson in 1925. Nightrider is used mostly in chess problems.

Nightrider can also give triple check.

Example

T. R. Dawson

British Chess Magazine, 1925

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#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#

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

	a	b	c	d	e	f	g	h
8									8
7									7
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	a	b	c	d	e	f	g	h

Mutual discovered perpetual check with nightriders.

Then a possible continuation would be: 1. Kd3+ Kc5+ 2. Kc3+ Kd5+ 3. Kd3+ Kc5+ etc.

	a	b	c	d	e	f	g	h
8									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 with en passant results in triple check.

References

• Hooper, David; Whyld, Kenneth (1992), The Oxford Companion to Chess (2nd ed.), Oxford University Press, ISBN 0-19-280049-3 

External links

• Nightrider problems on PDB Server