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.
All these factors, and many others, conspired to bring about the First World War. As is insinuated by the name the powder keg of Europe, the Balkans were not the major issue at stake in the war, but were merely the catalyst that led to the conflagration.