The endless need for food is common amongst all civilization, no matter the country.
After the last Ice Age, Agriculture was invented due to humans settling around the world.
Villages, cities, and agrarian civilization enervate new social systems and complex infrastructures that aid in agriculture.
More food = more people
All thresholds connect to energy. We learned how to better use the power of the sun to better our agriculture. Agriculture connects us all. Agriculture has become one of the vital necessities to survive as a society.
War = farming disrupted = less Agriculture = less food
Agricultural Adjustment Act passed by President Roosevelt And the Soil Conservation and Domestic Allotment Act.