US and what were the three most critical development/changes that took place during this time in regard to influencing our modern society?????|||The civil war changed many things in the United States, it was considered the first modern war of it%26#039;s time. The war forced many new inventions, such as new weapons and canned food, medical treatment of soldiers and thy way they were moved around. Trains and boats were used to move troops from one area to another. Storing of foods for the troops and the use of canning to keep the food from spoiling.
New businesses had to be set up to rebuild the devastated south and more industry sprang up in the north as more immigrants came over.
