The Republic of Venice lost its independence when Napoleon Bonaparte conquered Venice on 12 May 1797 during the War of the First Coalition. Napoleon was seen as something of a liberator by the city's Jewish population. He removed the gates of the Ghetto and ended the restrictions on when and where Jews could live and travel in the city.

Venice became Austrian territory when Napoleon signed the Treaty of Campo Formio on 12 October 1797. The Austrians took control of the city on 18 January 1798. Venice was taken from Austria by the Treaty of Pressburg in 1805 and became part of Napoleon's Kingdom of Italy. It was returned to Austria following Napoleon's defeat in 1814, when it became part of the Austrian-held Kingdom of Lombardy–Venetia. In 1848 a revolt briefly re-established the Venetian republic under Daniele Manin, but this was crushed in 1849. In 1866, after the Third Italian War of Independence, Venice, along with the rest of the Veneto, became part of the newly created Kingdom of Italy.
Was Venice always part of Italy?
Venice started off with refugees from neighboring Roman cities such as Padua, Aquileia, Treviso, Altino etc., and developed into a powerful maritime empire, a republic in it's own right.   In 1797, Venice was conquered by Napoleon Bonaparte and switched several times between being an Austrian territory,  part of the Kingdom of Italy, back to being part of Austria and eventually after the Italian Independence War of 1866 to being part of Italy.