The history of Jesolo is very much linked to Venice. Jesolo has in fact preceded Venice in the annals of history and has given an important contribution to the making of the lagoon city. Ancient Roman centre, as many archaeological findings witness, Jesolum became one of the most flourishing ports of the lagoon Confederation, within the period that goes from the fall of the Roman Empire to the birth of Venice. During the upper Middle Ages, Jesolo was known as Equilium. In 742 Jesolo was opposed to Eraclea, which preceded Malamocco and Rialto as the seat of Dogado. Destroyed in 806 by Pipino King of the Francs, Jesolo shortly rose again and was back as one of the main centres of the lagoon. Around the year 1000 it was Episcopal centre with 42 churches, many convents and salt-ponds. Then the decadence caused, as happened to Torcello, by the progressive silting up of the lagoon. In the XVI century the Republic of Venice started massive works of land reclamation, which caused the river Sile and the river Piave to have their routes changed in such a way that the aspect of the area was completely different, from a lagoon it was now a land brought under cultivation. During World War I, as from November 1917, Jesolo was a battle field for important fights aimed at backing up the German offensive after Caporetto. It was during this period that the most ancient proofs of the old Jesolo were destroyed, like the big Roman cathedra, of which we only have a few ruins left.