THE CASTLE
An alone move to Chess allows to move two pieces to my time, it is the
CASTLE.  (Do not believe the rumor that would want that, since a pawn can
advance two squares to its first move, two pawns could advance simultaneously
a square to their first move, this is only a affabulation!).

The castle fact participate the King and a Rook.  The King displaces two
squares to the corner, and the Rook passes it by over and placing to its
sides.  When the concerned Rook is the closest to the King, it is the Small
Castle and when it concerns the most distanced Rook of the King (side Crowns)
one undertakes then the Great Castle.
Several conditions have to be filled in order that the castle could be
undertaken.  First conditions of situation:  Squares between the King and the
Rook have to be emptied, there no longer has to be pieces between the two.  
The King does not have to be in check (attacked by an adverse piece) during
the castle.  On the contrary of what is sometimes asserted, the King can
to castle even if it has been put in check, provided that the ready check,
neither it, nor the Rook have to have moved.  The Castle is forbidden in
three case well precise:
* if the King or the Rook have moved in the course the game.
* if the King is attacked by an adverse piece to the moment where it would want
a castle.
* if the King has, in castling, pass by a square attacked by an adverse piece.