A fleet carrier is intended to operate with the main fleet and usually provides an offensive capability. These are the largest carriers capable of fast speeds. By comparison, escort carriers were developed to provide defense for convoys of ships. They were smaller and slower with lower numbers of aircraft carried.
The First World War was sparked in the Balkans in 1914 when members of Mlada Bosna, a revolutionary organization with predominately Serbian and pro-Yugoslav members, assassinated the Austro-Hungarian heir Archduke Franz Ferdinand of Austria in Bosnia and Herzegovina's capital, Sarajevo.
The Balkan powder keg was the name given to the Balkan region because of the secure and safe state it had before a minor issue led to World War I. The assassination of Franz Ferdinand, the heir to Austria-Hungary empire, and his wife, Sophie, ended the peaceful state of Europe.