September. General strategic drivers The importance of trade and economic interests to the participants is often underestimated; contemporaries viewed Dutch and English support for the Habsburg cause as primarily driven by a desire for access to Spanish markets in the Americas. Modern economists generally assume a constantly growing market, but the then dominant theory of Mercantilism viewed it as relatively static. Increasing one's share implied taking it from someone else, and the role of the state was to restrict foreign competition by attacking merchant ships and colonies. This expanded the war to North America, India, and other parts of Asia, with tariffs used as a policy weapon. From 1690 to 1704, English import duties on foreign goods increased by 400%, and the 1651–1663 Navigation Acts were a major factor in the Anglo-Dutch Wars. On 6 September 1700, France banned the import of English manufactured goods such as cloth, and imposed prohibitive duties on a wide range of others. Armies of the Nine Years' War often exceeded 100,000 men, levels unsustainable for pre-industrial economies; those of 1701–1714 averaged around 35,000 to 50,000. Dependence on water-borne transport for supplying these numbers meant campaigns were focused on rivers like the Rhine and Adda, which limited operations in poor areas like Northern Spain. Better logistics, unified command, and simpler internal lines of communication gave Bourbon armies an advantage over their opponents. Strategic objectives by participant Great Britain British foreign policy was based on three general principles, which remained largely consistent from the 16th through the 20th centuries. The first, overriding all others, was to preserve a balance of power in Europe, an objective threatened by French expansion under Louis XIV. The second was to prevent the Low Countries being controlled by a hostile power or one stronger than Britain; this included both the Spanish Netherlands and the Dutch Republic, whose deep harbours and prevailing winds made her a natural embarkation point for an attack on England, as demonstrated in 1688. The third was to maintain a navy strong enough to protect British trade, control her waters and launch attacks on her enemies' commercial routes and coastal areas. Alignment on reducing the power of France and securing the Protestant succession for the British throne masked differences on how to achieve them. In general, the Tories favoured a mercantilist strategy of using the Royal Navy to attack French and Spanish trade while protecting and expanding their