In 1433, Cosimo's power over Florence began to look like a menace to the anti-Medici party led by figures such as Palla Strozzi and the Albizzi family, headed by Rinaldo degli Albizzi. In September of that year, Cosimo was imprisoned in the Palazzo Vecchio for his part in a failure to conquer the Republic of Lucca, but he managed to turn the jail term into one of exile. Some prominent Florentines, such as Francesco Filelfo, demanded his execution, a fate that may have been almost certain without the intervention of the monk Ambrogio Traversari on his behalf. Cosimo traveled to Padua and then to Venice, taking his bank along with him and finding friends and sympathizers wherever he went for his willingness to accept exile rather than resume the bloody conflicts that had chronically afflicted the streets of Florence. Venice sent an envoy to Florence on his behalf and requested that they rescind the order of banishment. When they refused, Cosimo settled down in Venice, his brother Lorenzo accompanying him. However, prompted by his influence and his money, others followed him, such as the architect Michelozzo, whom Cosimo commissioned to design a library as a gift to the Venetian people. Within a year, the flight of capital from Florence was so great that the decree of exile had to be lifted. Cosimo returned a year later, in 1434, to influence the government of Florence (especially through the Pitti and Soderini families) for the last 30 years of his life of 75 years.