Chessmen Club

At the beginning the white pieces occupy the left and the black pieces the right half of the board, one field in the middle is empty.
The objective of the game is to swap the pieces of different color so that all the black pieces are on the left side and the white pieces are on the right side.
The fewer trains you need, the better.
You can move all the pieces, the rules are the same as in the normal game of chess - except capturing pieces is not possible.