e. Despite the existence of a series of defensive lines and switch positions between his present line and the PO, there can be little doubt that the enemy must always exercise maximum caution in the disposal of his strength so long as he remains south of this river. Allied offensive capabilities constitute a greater threat to his armies there than they would at any point beyond the PO. Ths enemy must therefore always lay great stress in his deliberations on two possible contingencies both of them involving potentially serious consequences.