French intervention in Italy trespassed on the emperor’s jurisdiction and disturbed the balance established by the Peace of Cherasco in 1631. In keeping with Richelieu’s general strategy, the attack on Spain’s possessions was not made alone, but in partnership with Italian princes. Known as the League of Rivoli, this alliance proved rather feeble. Savoy was the most potent member, fielding 12,250 professional troops in return for French backing for its royal ambitions and a promise of part of Milan. Mantua was still recovering from the earlier war and could provide only 3,000 men, while Parma sent another 4,500. The other Italian rulers remained neutral. Despite promises to his allies, Richelieu accorded Italy a low priority and it was not until October 1635 that the French army there reached 12,000 men. By then, operations had collapsed amid bickering between the French and Italian commanders.
Spain not only held its own in Lombardy but launched an amphibious counter-attack, capturing the Lérin islands off Provence in September. French attempts to recover them were repulsed in 1636–7, enabling Spain to disrupt the flow of aid to Richelieu’s allies. France made a more substantial effort against Lombardy in 1636, but still started a month late and at only two-thirds of intended strength. French forces helped repel an attack on Vercelli protecting Savoy, but the distraction allowed Spain to knock out Parma and Mantua by February 1637.
The fighting assumed some significance for the Empire by drawing imperial forces into the final struggle over the Valtellina. Spain’s use of the pass to intervene in Germany in 1633–4 convinced Richelieu that it had to be closed, and that the only way to do this was to restore Protestant Rhetian control over the Catholic inhabitants. He sent Henri de Rohan from Alsace across Protestant Swiss territory to join 2,000 Rhetians who had been raised with French money. The combined force of about 7,400 crossed the Splügen pass waist-deep in snow on 27 March 1635 to surprise the Spanish at Chiavenna at the south end of the valley. With this taken, the other garrisons further up were trapped and soon knocked out. Thus began one of the most daring and brilliantly led campaigns of the entire war. Rohan’s force was too weak to hold both ends of the valley simultaneously, so he took up position near the more vulnerable northern entrance at Bormio with detachments watching the south.
The Habsburg attempt to take the valley exposed the weakness in their military cooperation following Nördlingen. Gallas reluctantly detached 10,000 men under Fernemont and sent them to the Tirol to attack the northern end of the valley, but Cardinal Albornoz, the new Spanish governor of Milan, feared a Franco-Savoyard attack and only belatedly sent Count Serbelloni with 2,000 men to the south end. Fernemont advanced before the Spanish were ready. Rohan let him overrun the northern half of the valley, and then outflanked him using the Engadin, taking him by surprise and sending him packing by mid-July. Serbelloni had only just occupied the south entrance and quickly withdrew as Rohan turned against him. The failure of the Franco-Savoyard offensive against Milan by October 1635 emboldened the Habsburgs to take advantage of the mild autumn for another attempt. Fernemont had been reinforced to 15,000, while Serbelloni now mustered 5,000 men. Again, the Austrians moved prematurely and were defeated after heavy fighting by Rohan, whose superior understanding of mountain warfare enabled him to outflank them. The French then dashed south to rout the Spanish on 9 November.
Rohan had been welcomed by the Rhetians as ‘the Angel Gabriel in person’, but was put in an invidious position by Richelieu’s instructions not to let the Rhetians reimpose Protestantism on the valley. Spanish transit of the Valtellina in 1629–34 had brought the plague and halved the population. The 40,000 survivors struggled to feed even Rohan’s small force. The Rhetians had no interest in wider French objectives and refused to support Rohan’s attempted invasion of Milan in May 1636. The war’s return to the Alps heightened tension within the Swiss Confederation, where the Catholics allowed Spain to send its 10,000 German recruits through the St Gotthard pass that year to reinforce the Army of Lombardy, now under Leganés, who had replaced Albornoz.
Rohan was cut off. He owed his Rhetian infantry 1 million livres in pay arrears, and many of the officers shared their government’s suspicions of French intentions. Colonel Jenatsch, a former fundamentalist Protestant pastor who, for reasons unknown, had recently converted to Catholicism, led a mutiny among Rohan’s troops in October 1636 and seized strategic points along the valley. The Habsburgs were taken by surprise, but swiftly accepted his offer of an alliance on 17 January 1637, agreeing to drive the French out in return for Spain settling the soldiers’ pay arrears, while Austria rescinded its 1629 prohibition on Protestantism in the areas of the Ten Parish League under its jurisdiction. Rohan was obliged to withdraw his remaining French troops in April. The alliance with heretics was initially presented as a necessary evil, but by 1639 Spain abandoned its remaining scruples and formally returned the Valtellina to Rhetian control in return for guarantees the Free State would not tamper with the Catholic character of the valley and would allow Spain transit. The latter requirement was now largely worthless since French control of Alsace cut the Spanish Road. Nonetheless, the alliance secured the service of the Protestant Rhetians who comprised a seventh of Leganés’ army by 1640.
The Savoyard Civil War
French failure in Italy widened the divisions at the Savoyard court following the unsatisfactory outcome of the Mantuan War. Though Savoy had acquired the northern half of Monferrato, it had been obliged to surrender Pinerolo to France, giving that country access across its territory. Lorraine’s fate during the early 1630s underscored the dangers of such a position. French influence in the duchy grew following the death of Charles de Nevers in September 1637. French troops seized his part of Monferrato, including Casale, while the Venetians occupied Mantua. Tensions spilled over into war after Duke Vittorio Amedeo I’s death the following month.
The pro-French faction was led by Louis XIII’s sister, the duke’s widow Marie Christina, who acted as regent for her two young sons, the first of whom had already died by 1638. It is possible that she was jealous of her sisters, Henrietta Maria and Elisabeth who were respectively queens of England and Spain. Certainly, her own ambitions reflected those of a Savoy dynasty that already claimed royal blood based on alleged links to the kingdom of Cyprus. Richelieu manipulated these ambitions, saying that France could only recognize Savoy as a kingdom if it enlarged itself at Milan’s expense. Madame Reale, as she styled herself, was opposed by her two brothers-in-law, princes Tommaso and Cardinal Maurizio, whom she excluded from the regency. Tommaso had recently returned from serving in the Army of Flanders. He had married Marie, daughter of the duc de Bouillon, associating himself closely with the anti-Richelieu faction in France. Rumours circulated that Madame Reale had poisoned her husband to stop Savoy defecting to Spain. Tommaso and Maurizio also drew on resentment in the regions against Turin’s centralization. While these factors were important, the heart of the Savoyard civil war was a dynastic struggle for control of the regency.
The conflict between the madamisti and the principisti seriously undermined France’s position in Italy just as Richelieu wanted to withdraw forces to concentrate on the other fronts. The French rarely mustered over 10,000 men in the duchy, half of whom were needed to hold Casale and other fortresses. Leganés joined the principisti with 13,000 Spanish to capture Vercelli, Ivrea, Verue and Nice in 1638. French relations with Madame Reale deteriorated as Richelieu used her current predicament to pressure her to surrender her other garrisons to French control. Emperor Ferdinand exercised his imperial jurisdiction and declared Tommaso and Maurizio regents in March 1639 as the Spanish pushed deeper into Savoy. Tommaso entered the capital at the head of 10,500 men on 27 July, but Madame Reale escaped into the citadel with her 2,000 French guards. The remaining French forces agreed a truce lasting until October, which allowed the Spanish to extend their control over the duchy, while Tommaso blockaded his sister-in-law.
A new French army of 7,000 men arrived under the comte d’Harcourt and though it defeated the Spanish field force, it was unable to relieve the Turin citadel before winter. Leganés tried to divert Harcourt by besieging Casale early in 1640 to give Tommaso time to take the citadel. Harcourt stripped the remaining French garrisons to increase his field force and relieved Casale. Having received further reinforcements giving him 19,000 men in total, he appeared outside Turin in May. An extraordinary triple siege began. Madame Reale defended the citadel against Tommaso and 12,000 men, who were besieged in Turin by Harcourt, while Leganés and 17,000 Spanish troops surrounded Harcourt outside the city. Tommaso ran out of supplies first and broke out, allowing the French to relieve the citadel in November 1640.
The result was a stalemate. With only 8,000 effectives in the field, the French were unable to dislodge the Spanish from the captured towns, but the Catalan and Portuguese revolts at the end of the year prevented reinforcements reaching Leganés. Both Madame Reale and the princes realized that what they were fighting for was being destroyed in the process. Despite Spain holding his wife and children hostage, Tommaso opened negotiations with the French. He and his brother were accepted as co-regents in May 1642 and given large French pensions and their own palaces. Tommaso assumed command of the combined Franco-Savoyard army, which increased to 20,000 by the later 1640s. France returned Turin to Madame Reale, but kept a garrison in its citadel until 1657, securing the duchy’s allegiance for the remainder of the war.