The Black Hand was a secret Serbian nationalist organization that played a crucial role in the events leading up to World War I. Formed in the early 20th century, it aimed to promote Serbian nationalism and the creation of a Greater Serbia through violent means. The group's actions, particularly the assassination of Archduke Franz Ferdinand of Austria in 1914, acted as a catalyst for the outbreak of the war, highlighting the tensions between nationalistic fervor and imperial ambitions in Europe.