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Austria-Hungary Takes Control of Bosnia
Accused Serbia of subverting its rule over Bosnia. The "powder keg" was ready to explode. -
The Triple Entente is Formed
Informal coalition between Great Britain, France, and Russia. International tension increased. -
The Triple Alliance is Formed
Consisted of Germany, Austria-Hungary, and Italy. They provided a measure of security. -
Archduke Franz Ferdinand is Assassinated
Archduke Franz Ferdinand was visiting the Bosnian capital Sarajevo. Gavrilo Princip was standing among the crowd. He stepped forward and shot both the Archduke and his wife. Princip was part of the Black Hand, which promoted Serbian nationalism. -
Austria-Hungary Declares War on Serbia
The assassination of the Archduke of Austria by a Serbian terrorist motivated A-H to declare war on Serbia. Russia began to mobilize its troops after this declaration of war incase it needed to come to the defense of Serbia. -
Germany Invaded Belgium
Schlieffen Plan was used to invade Belgim. The plan included a holding action against Russia and a drive through Belgium to Paris. The two German armies would defeat Russia after France had fallen. Civilians fled in terror. -
A German U-Boat Sinks the Lusitania
The Lusitania, a British passenger ship, was sunk off the coast of Ireland by a German U-Boat in 1915. The Germans set up a counterblackade with U-boats, from Unterseeboot meaning submarine in German, in response to the British blockade. Any British ship that was located in the surrounding waters of Britain was to be sunk, sometimes without warning. 1,198 lives were lost, 128 of them were American. -
The First Battle of the Somme Begins
The British first used tanks during the Battle of Somme. The Battle of the Somme was one of the largest battles of the war. By the time fighting paused, the forces involved had suffered more than 1 million casualties, and it was the bloodiest military operations ever recorded. -
The Zimmerman Note is Discovered
The Zimmerman Note is a message sent by the German foreign minister to the German ambassador in Mexico. It proposed a German-Mexican alliance and promised to help Mexico regain Texas, New Mexico, and Arizona if the United States entered World War I. -
The United States Declares War on Germany
The United States declared that it wished to stay out of the war and demanded that Germany stop attacking passenger ships. Germany continued to attack American ships heading towards Britain. President Wilson asked Congress for permission to declare war, they approved.
