The Tiepolo conspiracy, seeking to seize power in the Republic of Venice, is thwarted after bloody street clashes in Venice. The suppression of the revolt will lead to the creation of the Council of Ten.

The Tiepolo conspiracy or Tiepolo-Querini conspiracy was an attempt to overthrow the government of the Republic of Venice under Doge Pietro Gradenigo. Headed by the disaffected patricians Bajamonte Tiepolo, Marco Querini, and Badoero Badoer but backed by a sizeable number of other patricians, churchmen, and commoners, the conspiracy resulted in a coup attempt on 15 June 1310, in which three columns, each led by one of the chief conspirators, were meant to converge on the Piazza San Marco, seize the Doge's Palace, and overthrow the Venetian government. Warned of the plot at the last minute, the Doge mobilized his followers and loyalist forces. Coupled with the conspirators' poor coordination, the Doge's decisive counter-action led to the coup's failure. Querini, the main driving force of the conspiracy, was killed in the subsequent fighting along with one of his sons. Badoer was captured while trying to cross the Venetian Lagoon from Padua and executed for treason. Tiepolo was pushed back and barricaded in the Rialto. The Great Council let Tiepolo and his main supporters leave in exile.