On 15 June, the Prussian Army invaded Saxony, an ally of Austria. On 2 July, Austria asked Napoleon to arrange an armistice between Italy, which had allied itself with Prussia, and Austria, in exchange for which France would receive Venetia. But on 3 July, the Prussian army crushed the Austrian army at the Battle of Königgrätz in Bohemia. The way to Vienna was open for the Prussians, and Austria asked for an armistice. The armistice was signed on 22 July; Prussia annexed the Kingdom of Hanover, the Electorate of Hesse-Kassel, the Duchy of Nassau and the Free City of Frankfurt, with a combined population of four million people.