Corsica and killings culminated in the assassination of Prefect Claude Érignac in 1998. In 2013, Corsica hosted the first three stages of the 100th Tour de France, which passed through the island for the first time in the event's 110-year history. Corsica was formed about 250 million years ago with the uplift of a granite backbone on the western side. About 50 million years ago sedimentary rock was pressed against this granite, forming the schists of the eastern side. It is the most mountainous island in the Mediterranean, a "mountain in the sea". It is also the fourth largest island in
History of Corsica to Corsica having been given the rank of lieutenant-general. After proclaiming the independence of Corsica, a constitution was adopted that made Corsica a kingdom in personal union with Great Britain, represented by a viceroy. The constitution was considered quite democratic for its time, with an elected Parliament and a Council. Sir Gilbert Elliot served as viceroy whereas Carlo Andrea Pozzo di Borgo served as head of government (effectively a prime minister). The island returned to French rule in 1796. From 1854 to 1857 the Société du Télégraphe Électrique or "The Mediterranean Electric Telegraph", a company started by John Watkins Brett,