Diplomacy
Charles pursued a risky and aggressive foreign policy. He sought as many allies as possible and regarded almost everyone, apart from Louis XI, as a potential ally. In 1471, he made a list of his nineteen allies. By the following year he counted twenty-four, and by 1473 he claimed twenty-six allies, compared with Louis XI's fifteen. Some of these relationships, however, were largely formal, such as those with Scotland. The kings of Scotland and Denmark also signed treaties with Louis XI and appeared on his own list of allies.
Initially, Charles was hesitant about an alliance with Matthias Corvinus, king of Hungary. However, Burgundy and Hungary were drawn closer by their shared friendship with the Kingdom of Naples. At the same time, Charles sought contact with Matthias as part of his wider effort to ally with Frederick III's opponents. Charles hoped that by supporting Matthias's claim to the Kingdom of Bohemia, Matthias would back him in the electoral college. In November 1474, the two concluded a treaty under which they agreed to partition the Holy Roman Empire between themselves: Charles would become king of the Romans and rule the lands along the Rhine, while Matthias would acquire Breslau and Bohemia.
In 1473, through negotiations with the new Duke of Lorraine, René II, Charles secured the right to move his armies through Lorraine and place Burgundian captains in its important fortifications, effectively turning the duchy into a Burgundian protectorate. Among Charles's other allies were Amadeus IX, Duke of Savoy, whose wife, Yolande of Valois, Louis XI's sister, drew the duchy into an alliance with Burgundy through her hostility to her brother.
The intense rivalry between Louis XI and Charles kept both rulers prepared for war. In 1468, Charles and Louis attempted a reconciliation, which astonished the rest of France. Their peace talks quickly turned to hostility when Charles learned that Louis had been involved in a recent rebellion in Liège. Charles then detained Louis at Péronne and compelled him to sign a treaty favourable to Burgundy. Its terms released the Duke of Burgundy from the obligation of paying homage, recognised Charles's sovereignty over Picardy, and ended French jurisdiction over Burgundian subjects. Louis reluctantly agreed and signed the Treaty of Péronne. The French crown, however, did not abide by its terms, and Franco-Burgundian relations remained poor.
The suspicious death of Charles of Valois, Duke of Berry, the king's brother, in 1472 prompted Charles to raise arms in revenge for the death of his ally, claiming that Berry had been poisoned by Louis. After a short conflict, the two ceased fighting in the winter of 1473 without making peace. Neither ruler formally declared war on the other again during the rest of their reigns.
At the start of Louis XI's reign, Italy's triple alliance between the Duchy of Milan, the Republic of Florence, and the Kingdom of Naples allowed French influence to grow in the peninsula, since Milan and Florence were long-standing allies of Louis. To counter this, Charles expanded Burgundy's sphere of influence in Italy in order to rival that of France. The first Burgundian alliance with an Italian ruler was with King Ferdinand I of Naples, who was admired by both Charles and Louis.
Ferdinand was the legitimised bastard of Alfonso I, and the Pope did not recognise his claim to the throne. Meanwhile, René of Anjou, the deposed King of Naples, continued to press his claim. Fearing an invasion by René or his heirs, supported by Louis XI, Ferdinand allied himself with Charles, who admitted him to the Order of the Golden Fleece in 1473. Charles also considered marrying his daughter, Mary, to Ferdinand's second son, Frederick of Naples, who visited the Burgundian court in 1474 and 1475.
In 1474, when war against Louis XI was looming, Ferdinand made his participation dependent on his son's marriage to Mary. Charles hinted that he was willing to agree, and Ferdinand dispatched his son to Burgundy on 24 October 1474. Although Frederick became a lieutenant and close military advisor to Charles, he failed in his ultimate mission of marrying Mary.
The Duchy of Milan was France's most important ally in the Italian peninsula. Its ruler, Galeazzo Maria Sforza was tied to the French Crown through his marriage with Louis XI's niece, Bona of Savoy. Charles nevertheless sought an alliance with Milan. In 1470, he offered Galeazzo membership in the Order of the Golden Fleece, as part of a proposed alliance, but was rejected. At one point he even included Milan on one of his lists of allies, which caused Galeazzo to protest.
To draw Galeazzo into alliance, Charles spread a rumour that he intended to conquer Milan. Fear of war, together with Charles's diplomatic pressure to isolate Milan from France, persuaded Galeazzo to sign a treaty at Moncalieri on 30 January 1475, creating an alliance between Savoy, Burgundy, and Milan. As a result, diplomatic relations were established between Burgundy and Milan, and Galeazzo sent Giovanni Pietro Panigarola as his envoy to Burgundy.
Charles's relations with the Republic of Venice rested on his professed willingness to launch a crusade against the Turks. At the insistence of Ferdinand of Naples, the senate of Venice agreed to a treaty against the King of France on 20 March 1472. Thereafter, Venice repeatedly urged Charles to fulfil his part of the bargain and support Venice in its war with the Ottomans. His inaction gradually led to estrangement between Burgundy and Venice.
As relations between Burgundy and Venice deteriorated, Charles sought to recruit the Venetian condottiero Bartolomeo Colleoni, who could have brought 10,000 men-at-arms with him, but the Venetian government refused to let him go. Charles spent two years negotiating with the Venetian ambassadors, but in the end failed to convince them. By 1475, the alliance between Venice and Burgundy had ceased to function as a genuine partnership.
The Italian peninsula saw a shift in spheres of influence after the Treaty of Moncalieri in 1475. Charles replaced Louis XI as the dominant influence in Italian politics, with three of four major secular powers in the region—Milan, Naples, and Venice—aligned with him. Only Florence remained a French ally, though it remained neutral toward Charles because of its alliance with Venice. Charles thus eliminated the prospect of Italian support for France and could expect support from his Italian allies if war with France resumed.
