This is the term for when countries pledge to assist each other if one of them gets in a conflict.
Alliance
This is the name of the alliance that had Russia, France, Britain, and eventually the U.S.
The Allies
This method of warfare was not new, but it was used in WWI and was the reason the war was so ineffective and why it was a stalemate for so long.
Trench Warfare
This is the term for extreme pride in a country.
Nationalism
This is the name of the alliance that contained Germany, the Austria-Hungarian Empire, and the Ottoman Empire.
The Central Powers
This was the invention the Germans used in WWI without restriction - sinking ships that were in British waters (no matter where the ship was from).
U-Boats
This is the stockpiling of weapons and the glorification of the military.
Militarism
This is the name of the person who was assassinated (the death that kicked of the war).
Franz Ferdinand
This was the invention that allowed soldiers to mow over barbed wire and other hazards in no-man's-land.
Tanks
This is the term for when a country takes over the social, political, or economic aspects of another country.
Imperialism
This is the name of the plan Germany had for the plan to surprise attack France through Belgium.
The Schlieffen Plan.
The Selective Service Act
This is the main reason people in the United States were willing to get involved in the War.
Germany's submarine tactics and the Lusitania.
This is the name of the conscientious objector who ended up joining the war for the U.S. (making a huge difference).
Alvin York
This is the name for the technique Allies used to protect merchant ships (and supply ships) from the Germans. It involved surrounding these ships with destroyer ships.
Convoys