He gathered a fleet at Ravenna, captured Chioggia, and pushed on up the Lido towards the capital of the lagoons at Malamocco.
It was not till the invasions of Hun and Langobard that fugitives from the Venetian mainland took refuge among the poor fishermen on the small islands in the lagoons and on the lido - the narrow stretch of coast-line which separates the lagoons from the Adriatic - some at Grado, some at Malamocco, others on Rialto.
The point of San Nicolo del Lido is strongly fortified to protect the new entrance to the port (see harbour).
The government accordingly resolved to reopen the Lido entrance to the lagoon, and thus to afford a shorter and more commodious access from the sea.
The form it took was a solemn procession of boats, headed by the doge's maesta nave, afterwards the Bucentaur (from 1311) out to sea by the Lido port.
But with the decline of Venice the trade of the port fell off; the mouth of the Lido entrance became gradually silted up owing to the joint action of the tide and the current, and for many years complete stagnation characterized the port.
Under the republic commercial shipping used to enter Venice by the Tort of San Nicole del Lido and lie along the quay called the Riva degli Schiavoni, in the basin of San Marco, and up the broad Giudecca Canal.
The Austrians, abandoning the nearer Lido entrance to the lagoons, resolved to deepen and keep open the Malamocco entrance.
The intricate water-ways and the stubborn Venetian defence baffled all his attempts to reach Rialto; the summer heats came on; the Lido was unhealthy.