Theory i believe? hope this helps
It switched everything around
When President Truman took a hard line against striking workers in the years immediately following World War II, he:
"had little understanding of the plight of laborers in the post-war years."
During the first months of his administration, he became involved in a struggle between coal miners and railroad workers. It took several meetings, and fierce arguments, to get them to agree, and end the strike.
Feudalism was successful because it allowed the control of land in exchange for service or labor.