The early-mid 15th century saw a steady consolidation of the medieval city-states of northern Italy. In 1454, three of the most powerful states, Milan, Florence and Naples settled their territorial differences at the Peace of Lodi. There was calm until the 1490s, when Ludovico Sforza invited the armies of France, then the Holy Roman Empire, into Italy. This unleashed half a century of foreign invasions and internecine conflict in Italy. One early consequence was that, through France’s diplomatic and military ineptness, the Kingdom of Naples fell to Spain in 1503. The Papal States were major players in the conflicts, firstly by proxy, in the Borgia Pope Alexander VI’s sponsorship of his son Cesare’s campaigns, and directly by the warrior Pope Julius II. In the name of the ’Holy League’ Julius II declared war on Venice, made Venice an ally, and went on to fight with Venetians against France.