A controversy involved the decision whether Polish forces should defend the lengthy borders or should withdraw east and south and try to defend a shorter line, backed with rivers. Although the second plan was more militarily sound, political considerations outweighed them, as Polish politicians were concerned that Germany could be satisfied with occupation of some disputed territories (like the Free City of Danzig, the Polish Corridor and Silesia) and then push for an early end of the war after it had occupied those territories. The western regions were also the most densely populated ones and had major industrial centres, which were crucial for mobilization and any continued military production of equipment and supply for the Polish Army.