Answer: German submarines threats the U.S
Explanation:
Answer:
Heavy artillery, machine guns, tanks, motorized transport vehicles, high explosives, chemical weapons, airplanes, field radios and telephones, aerial reconnaissance cameras, and rapidly advancing medical technology and science were just a few of the areas that reshaped twentieth century warfare.
The cause of the civil war was about no slave and for the USA to be free to all.
Greece's main exports were olive oil, wine, pottery, and metalwork