What did are the things that the two main groups carried that they humped?

The men humped burdens that were personal..... love, emotions, responsibilities, and memories.

To carry something was to hump it, as when Lieutenant Jimmy Cross humped his love for Martha up the hills and through the swamps. In its intransitive form, to hump meant to walk, or to march, but it implied burdens far beyond the intransitive. Almost everyone humped photographs.

Lieutenant Cross carried two photographs of Martha.