Leader of the Risorgimento (Italian national unity movement) in Venice.
The son of a converted Jewish lawyer (who had taken his sponsors historic name at baptism), he studied law at Padua, graduating at 17.
In his first several years as a practicing lawyer he showed little interest in politics and disapproved of the conspiratorial activities of the Carbonari and other revolutionary groups.
In the late 1840s he underwent a change and joined the patriot Nicolò Tommaseo in giving expression to the discontent of the Venetian people under Austrian rule.
When Manin presented a petition for home rule to the Congregation, the quasi-representative body of the Austrian province of Venezia, he was imprisoned along with Tommaseo (January 1848). After the risings of the following March he was freed and made president of the Venetian Republic in which capacity he reluctantly accepted the project of unionn with the kingdom of Piedmont-Sardinia in the name of Italian unification.
He led a heroic defense of Venice against an Austrian siege even after the defeat of the Piedmontese army at Novara; when cholera and bombardment finally forced surrender in August 1849 he was among those excepted from amnesty and was banished.
For the remainder of his life he lived in Paris where he strove to enlist French sympathy for the Italian cause. In 1868, eleven years after his death his body was returned to liberated Venice for a state funeral.