(i) President Roosevelt realized that the United States had to change its policy of isolation, but could not intervene directly in the War in Europe, because it was not politically feasible.
(ii) So he started a program of "Lend Lease" in March 1941. Arms, food, military equipment, and other supplies were sent to Britain, disguised as a "loan", which would be returned after use.

(i) Battle of Britain- By July 1940, it was feared that the Germans were planning to invade Britain.
(ii) Hitler wanted to force Britain to accept his proposals for peace by a prolonged airborne bombing campaign.
(iii) The German air force began to attack specific targets, especially the ports, airfields, and industrial installations.
(iv) In September 1940, London was bombed mercilessly, an action known as The Blitz.
(v) By October 1940, night bombing raids on London and other industrial cities began.

(i) World War II was a modern war fought with heavy military equipment such as tanks, submarines, battleships, aircraft carriers, fighter planes, and bomber planes.
(ii) This involved a very large resource base, since all this equipment needed to be manufactured.
(iii) There had to be raw materials, manufacturing capacity and technical inputs to improve the military hardware. This was an expensive and prolonged war of attrition.

(i) Germany experienced both high unemployment and severe inflation after the War, and its currency became practically worthless.
(ii) There are several pictures of the 1920s when ordinary people had to carry money in wheelbarrows to buy bread.

While the world at large had experienced many wars, these two wars are referred to as "World wars" because of the extended areas of the conflict and the very high death toll of civilians as well as armed combatants. Both wars were fought on several fronts across Europe, Asia, and Africa.