Developments in 19th-century Europe are bounded by two great events. The French Revolution broke out in 1789, and its effects reverberated throughout much of Europe for many decades. World War I began in 1914. Its inception resulted from many trends in European society, culture, and diplomacy during the late 19th century. In between these boundaries—the one opening a new set of trends, the other bringing long-standing tensions to a head—much of modern Europe was defined.