of the Habsburgs by financing their opponents, including the Dutch, clients in Northern Italy and the Grisons, the Ottomans, the Venetian Republic, Transylvania, and Sweden. After 1635, France intervened directly through anti-Habsburg alliances with the Dutch and Swedish, while supporting insurgents in Portugal, Catalonia and Naples For their part, the Habsburgs backed the Huguenots and numerous conspiracies led by the feudal lords who resented their loss of power under Cardinal Richelieu and his successor, Cardinal Mazarin. The most significant included the 1632 Montmorency plot, the 1641 Princes des Paix rising, and Cinq-Mars in 1642. Spain also financed the 1648 to 1653 civil war known as the Fronde. Wider co-operation between the Spanish and Austrian Habsburgs was limited, since their objectives did not always align; Spain was a global maritime power, Austria primarily a European land power, focused on the Holy Roman Empire, which contained over 1,800 members, most extremely small. Although a Habsburg had been Holy Roman Emperor since 1440, their control over the Empire was weakened by the 1555 Peace of Augsburg, and this continued in the period leading up to 1620. Reversing this trend was a major Habsburg objective during the Thirty Years War, but they acknowledged failure in the 1648 Treaty of Westphalia. France faced the same issue of diverging objectives with its allies. The war coincided with the period of economic supremacy known as the Dutch Golden Age, and by 1640, many Dutch statesmen viewed French ambitions in the Spanish Netherlands as a threat. Unlike France, Swedish war aims were restricted to Germany, and in 1641, they considered a separate peace with Ferdinand. From the late 16th century, Italy, especially the Kingdom of Naples, was the primary source of soldiers and money for the Spanish Army of Flanders. As a result, much of the fighting focused on the Spanish Road, an overland supply route connecting Spanish possessions in Italy with Flanders, but which also passed through areas considered vital to French security, like Alsace. The independent Duchy of Savoy and Spanish-held Duchy of Milan were not only strategically important to the Road, but also provided access to the vulnerable southern borders of France, and Habsburg territories in Austria. Richelieu aimed to end Spanish dominance in these areas, an objective largely achieved by the time he died in 1642. Until the advent of railways in the 19th century, water was the primary means of bulk transportation, and