The nightrider, alternatively spelled knightrider and also known as the knightmare or unicorn (though the latter term sometimes refers to the

bishop A bishop is an ordained member of the clergy who is entrusted with a position of Episcopal polity, authority and oversight in a religious institution. In Christianity, bishops are normally responsible for the governance and administration of di ...

+nightrider compound), is a

fairy chess piece A fairy chess piece, variant chess piece, unorthodox chess piece, or heterodox chess piece is a chess piece not used in conventional chess but incorporated into certain chess variants and some unorthodox chess problems, known as fairy chess. Compar ...

that can move any number of steps as a

knight A knight is a person granted an honorary title of a knighthood by a head of state (including the pope) or representative for service to the monarch, the church, or the country, especially in a military capacity. The concept of a knighthood ...

in the same direction. The nightrider is often represented by an altered version of the knight's icon. In this article, the nightrider is represented by an inverted knight and notated as ''N'', while the knight is abbreviated as ''S'' for the German name ''Springer''. The nightrider was invented by W. S. Andrews in 1907 and named by Thomas Rayner Dawson, who first used it in

fairy chess Fairy chess is the area of chess composition in which there are some changes to the rules of chess. It may involve changes to the board, pieces, or rules to express an idea or theme impossible in orthodox chess. An altered piece used in fairy ...

problems in 1925.Hooper & Whyld (1996), p. 271

Movement

The nightrider moves and captures any number of steps as a knight (2 vertically and 1 horizontally, or 2 horizontally and 1 vertically) in the same direction. Intervening landing squares must be vacant. For example, a nightrider on b2 can reach the empty square c4 and continue forward to empty squares d6 and e8, but it cannot jump over a pawn on f4 to reach h5.

Value

The nightrider is worth about 5 pawns, similar to the rook. It can control up to 12 squares on an 8×8 board as opposed to the rook's 14. It is stronger than the rook in the opening and middlegame, as it can more easily maneuver around pieces than the rook, but the rook is stronger in the endgame. While king and rook vs. king can , king and nightrider vs. king cannot checkmate at all. The nightrider, like the knight, can jump over blockades in closed positions and is good at delivering forks. The nightrider can triangulate while the knight cannot. King, nightrider, and knight vs. king can force checkmate.

Observations

The king together with two knights cannot win the endgame against a lone king (see

Two knights endgame The two knights endgame is a chess endgame with a king and two knights versus a king. In contrast to a king and two bishops (on opposite-colored squares), or a bishop and a knight, a king and two knights cannot checkmate against a lone king (h ...

), but the king together with a knight and a nightrider can. This is because, unlike the knight, the nightrider can gain a

tempo In musical terminology, tempo (Italian for 'time'; plural 'tempos', or from the Italian plural), measured in beats per minute, is the speed or pace of a given musical composition, composition, and is often also an indication of the composition ...

. 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 In the game of chess, perpetual check is a situation in which one player can play an unending series of checks from which the defending player cannot escape. This typically arises when the player who is checking feels their position in the game i ...

is possible. A possible continuation would be: 1. Kd3+ Kc5+ 2. Kc3+ Kd5+ 3. Kd3+ Kc5+, etc. In the diagrammed position, 1...e5 2.fxe6+ (capturing ''

en passant In chess, ''en passant'' (, "in passing") describes the capture by a Pawn (chess), pawn of an enemy pawn on the same and an adjacent that has just made an initial two-square advance. This is a special case in the rules of chess. The capturi ...

'') results in triple check.

References

Bibliography * {{Chess piece Fairy chess pieces 1925 introductions