Nationalism: One country attacking another country.
Alliances: Innocent countries could get dragged into a war making allies.
Imperialism: One empire owns two countries.
Militarism: When a country with huge army waiting on an excuse to use it.
The immediate cause of World War I that made the aforementioned items come into play (alliances, imperialism, militarism, nationalism) was the assassination of Archduke Franz Ferdinand of Austria-Hungary. In June 1914.
Technology: Tanks, machine guns, planes, radio, radar. Medical: first-aid stations, triage of the wounded, evacuation to hospitals behind the lines, and training of personnel. And the use of X-Ray machines. Communication: During WW1, telephones were used, along with telegraph, Morse Code, and radio's.
The Allies included Britain, France, Russia, Italy and the United States. These countries fought against the Central Powers which included Germany, Austria-Hungary, Ottoman Empire and Bulgaria.
Isolation is used for seperating, but in WW1 they seperated countries which empires didn't like. But now there are no empires, so a county could get split up and there is no stopping it. The Treaty of Versailes was a treaty between U.S. and Germany. The U.S. won the war which was supposed to be the war to end all wars, but Germany disobeyed the treaty, so now we can't trust Germany.
The American Home Front was when women had to come into roles that the men serving in war had previously held. They supplied the military with weapons, machinery, food.