The battles of Magenta and Solferino left Franco-Piedmontese forces in control of Lombardy, but the Austrians remained confident of defending their "fortress quadrilateral" area, with four fortresses in Verona, Legnago, Peschiera, and Mantua. These defenses, the horrors of the Battle of Solferino, the possibility of Prussian entry into the war, and the potential for an over-strong Piedmontese state convinced Napoleon to sign a separate peace with Austria in the Treaty of Villafranca on 11 July 1859, ending the Second Italian War of Independence. Victor Emmanuel accepted the peace, but Cavour was so infuriated after reading the terms of the treaty that he tendered his resignation. He soon regained his optimism, however, as several of the terms, such as the restoration to power of the rulers of Tuscany and Modena, and the establishment of an Italian Confederation including Austria, were not actually carried out.