Final answer:
Gavrilo Princip, a young Serbian nationalist, assassinated Archduke Franz Ferdinand and his wife Sophie, triggering the start of the First World War.
Step-by-step explanation:
The assassination of the Austro-Hungarian prince that started the First World War was carried out by Gavrilo Princip, a young Serbian nationalist. On June 28, 1914, Princip shot and killed Archduke Franz Ferdinand and his wife Sophie in Sarajevo, Bosnia.
This event triggered a series of diplomatic and military actions that eventually led to the outbreak of the war. Gavrilo Princip, a young Serbian nationalist, assassinated Archduke Franz Ferdinand and his wife Sophie, triggering the start of the First World War.