who rules if the king is too young
Regency Acts According to the Regency Acts in force, if the monarch is under the age of 18 years when he or she succeeds to the Throne, a regency is automatically established, and, until the monarch attains the age of 18 years, the royal functions are discharged by the regent in the name and on behalf of the monarch.
King (chess) In conjunction with a rook, the king may make a special move called castling, in which the king moves two squares toward one of its rooks and then the rook is placed on the square over which the king crossed. Castling is allowed only when neither the king nor the castling rook has previously moved, no squares between them are occupied, the king is not in check, and the king will not move across or end its movement on a square that is under enemy attack.