English: THE OPTION OFFERED TO THE GERMAN SUBMARINES This diagram explains why the American navy succeeded in transporting more than 2,000,000 American soldiers to France without loss because of submarines. The Atlantic was divided into two broad areas shown by the shaded parts of the diagram. Through the northern area were sent practically all the merchant ships with supplies of food and materials for Europe. The southern area, extending roughly from the forty-fifth to the forty-ninth parallel, was used almost exclusively for troopships. The Germans could keep only eight or ten U-boats at the same time in the eastern Atlantic ; they thus were forced to choose whether they should devote these boats to attacking mercantile or troop convoys. The text explains why, under these circumstances, they were compelled to use nearly all their forces against merchant ships and leave troop transports practically alone.