Within the Kingdom of Lombardy-Venetia, the revolution in Vienna sparked anti-Habsburg riots in the cities of Milan and Venice. Austrian Field Marshal Joseph Radetzky was unable to defeat the Venetian and Milanese insurgents in Lombardy-Venetia, and had to order his forces to evacuate western Italy, pulling his troops back to a chain of defensive fortresses between Milan and Venice known as the Quadrilatero. With Vienna itself in the middle of an uprising against the Habsburg Monarchy, the Austrian Empire appeared on the brink of collapse. On 23 March 1848, just one day after Radetzky was forced to retreat from Milan, The Kingdom of Sardinia sought to capitalize on the chaos engulfing the Austrian Empire and declared war, sparking the First Italian War of Independence.