The Queen is usually reckoned equal, in average situations, to two Rooks and a Pawn, but towards the end of a game she is hardly so valuable as two Rooks.
Howard StauntonA player is said to have the opposition when he can place his King directly in front of the adverse King, with only one square between them. This is often an important advantage in ending games.
Howard StauntonIn Castling, the King must be moved first, or before the Rook is quitted. If the Rook be quitted before the King is touched, the opposing player may demand that the move of the Rook shall stand without the Castling being completed.
Howard Staunton