In the St. Lawrence and Mohawk theatres of the conflict, the French had begun to challenge the claims of Anglo-American traders and land speculators for supremacy in the Ohio Country to the west of the Appalachian Mountains—land that was claimed by some of the British colonies in their royal charters. In 1753, the French started the military occupation of the Ohio Country by building a series of forts. In 1755, the British sent two regiments to North America to drive the French from these forts, but these were destroyed by French Canadians and First Nations as they approached Fort Duquesne. War was formally declared in 1756, and six French regiments of "troupes de terre", or line infantry, came under the command of a newly arrived general, 44-year-old Marquis de Montcalm.