1.
No Man's Land: This is the area between the trenches.
2.
Stalemate: A situation in which neither side can gain the upper hand in war.
3.
The Allies (WWI): An alliance of WWI which included France, Britain, Russia and (later) the US. It also included Italy and Serbia.
4.
The Battle of Tannenberg: Disastrous defeat of the Russians on the Eastern front as they were repulsed after trying to invade Germany.
5.
The Battle of the Somme: Major offensive by the British against the Germans in July of 1916. Each side lost more than 500,000 casualties in this disastrous battle.
6.
The Battle of Verdun: Major offensive by the Germans in February of 1916. Each side lost more than 300,000 men in this disastrous offensive.
7.
The Central Powers: An alliance of WWI that included Germany, Austria, and (later) the Ottoman Empire and Bulgaria
8.
The Eastern Front: This was the theater of war in Russia. It pitted the Russian against the Germans and Austrians.
9.
The Schlieffen Plan: This was a German plan for winning WWI by throwing the majority of its forces against France, by attacking the French through Belgium, before turning their attention to Russia.
10.
The Western Front: This was the theater of war that was in France. It pitted the Germans against the French and British (and later the Americans).
11.
Trench Warfare: Style of warfare in which troops fought each other from defensive ditches dug just miles apart from one another. This generally led to a stalemate.
