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 (however, the superior side can force stalemate). Although there are checkmate positions, a king and two knights cannot them against proper, relatively easy defense. Paradoxically, although the king and two knights cannot checkmate of the lone king, there are positions in which the king and two knights can force checkmate against a king and some additional material. The extra material of the defending side provides moves that prevent the defending king from being stalemated. The winning chances with two knights are insignificant except against a few pawns. These positions were studied extensively by A. A. Troitsky, who discovered the Troitsky line, a line on or behind which the defending side's pawn must be securely blockaded for the attacking side to win. If the side with the knights carelessly captures the other side's extra material, the game devolves to the basic two knights endgame, and the opportunity to force checkmate may be lost. When the defender has a single pawn, the technique (when it is possible) is to block the pawn with one knight, and use the king and the other knight to force the opposing king into a corner or nearby the blocking knight. Then, when the block on the pawn is removed, the knight that was used to block the pawn can be used to checkmate. Checkmate possibilities In general, two knights cannot force checkmate, but they can force stalemate. Three knights can force checkmate, even if the defending king also has a knight or a bishop. Edmar Mednis stated that this inability to force checkmate is "one of the great injustices of chess." Unlike some other theoretically drawn endgames, such as a rook and bishop versus rook, the defender has an easy task in all endings with two knights versus a lone king. Players simply have to avoid moving into a position in which the king can be checkmated on the next move, and there is always another move available in such situations. Two knights In the corner The player with the lone king has to make a blunder to be checkmated. In this position, 1.Ne7 or 1.Nh6 immediately stalemates Black. White can