How did WW2 change the way humans fought wars?

Explanation:

World War II was the deadliest military conflict in history in terms of total dead, with some 75 million people casualties including military and civilians, or around 3% of the world's population at the time. Many civilians died because of deliberate genocide, massacres, mass-bombings, disease, and starvation.

president franklin roosevelt supported the tva as part of his first new deal measures approved by congress in 1933. this new agency was designed to control floods, produce electric power, and improve the lives of people living in the tennessee valley. the tva accomplished many of these goals despite problems.

the tariff was created to protect industry in the northern part of the united states. industries in the north were being driven out of business by imported goods that were priced at a low rate. the goal was to protect these industries   by taxing the goods.