World War 1 began in 1914 after the assassination of Archduke Francis Ferdinand of Austria-Hungary by Serbian nationalists. Germany then invaded Belgium following the Schlieffen Plan, which led to trench warfare along the Western Front in France. The war quickly became a bloody stalemate as the use of trenches and machine guns caused massive casualties. Though the U.S. initially remained neutral, American entry into the war in 1917 was prompted by Germany's resumption of unrestricted submarine warfare and the intercepted Zimmerman Telegram proposing a German-Mexican alliance against the U.S.

1. World War 1 Begins
CH. 11 SECTION 1

2. Causes of WWI
The Ammo
Nationalism
The Trigger The Explosion
Imperialism
Assassination of
Archduke Francis WWI
Ferdinand
Militarism
Alliance System

3. The War Starts
 1914 Germany follows Schlieffen Plan and invades
Belgium
 Trench Warfare began in France near the Marne
River
 3 kinds of trenches- front line, support, reserve
 “no mans land” lay between enemy trenches
 Led to a stalemate and the loss of thousands of lives

4. Divided Loyalties
 Many US immigrants still had ties in countries where
war was being fought
 Many Americans did not want their sons to suffer the
horrors of war
 Many also felt close ties to Britain because of their
common heritage
 America’s economic ties were far stronger with the
allies than the central powers

5. War Hits Home
 British blockaded German coast to prevent weapons
and supplies from getting through
 The US was upset about the blockade because it limited
freedom of the seas
 Germany responded with a counter blockade by U-
boats- they sunk any British or allied ship found in
the waters around Britain with no warning
 May 7, 1915 a U-boat sank the Lusitania killing over 100
innocent US citizens
 US did not respond militarily, but instead convinced Germany
to change its tactics

6. The U.S. Declares War
 Germany resumed unrestricted submarine warfare
 Zimmerman Note: a telegram intercepted by the
British proposing and alliance between Germany and
Mexico, and stating that the Germans would support
Mexico in recovering lost territory
 The Russian Monarchy was overthrown and Russia
withdrew from the war
 US declared war on April 2, 1917