28 June 1914 - the assasination of Archduke Franz Ferdinand of Austria and his wife Sophie.
Franz Ferdinand (nephew of Emperor Franz Josef and heir to the Austro-Hungarian Empire) and Sophie were touring Sarajevo in an open car when Serbian nationalist Nedjelko Cabrinovic threw a bomb at their car; it rolled off the back of the vehicle and wounded an officer and some bystanders.
Later that day, on the way to visit the injured officer, the archduke’s procession took a wrong turn at the junction of Appel quay and Franzjosefstrasse, where one of Cabrinovic’s cohorts, 19-year-old Gavrilo Princip, happened to be loitering.
Seeing his opportunity, Princip fired into the car, shooting Franz Ferdinand and Sophie at point-blank range. Princip then turned the gun on himself, but was prevented from shooting it by a bystander who threw himself upon the young assassin. A mob of angry onlookers attacked Princip, who fought back and was subsequently wrestled away by the police. Meanwhile, Franz Ferdinand and Sophie lay fatally wounded in their limousine as it rushed to seek help; they both died within the hour.
The assassination led directly to the First World War when Austria-Hungary subsequently issued an ultimatum to the Kingdom of Serbia, which was partially rejected. Austria-Hungary then declared war, triggering actions leading to war between most European states.