Rivers and lakes were the superhighways of the eighteenth century, and in the Colony of New York they either bordered New France in Canada or connected border waters to the interior of the colonies and the continent, allowing all sides in the French and Indian War to use them for attacks. The French sought to defend their frontiers by controlling the fur trade with American Indians, building alliances through missionaries who also tried to convert American Indians to their religious beliefs, and linking New France with the Louisiana Territory. The British aimed to protect the colonies from Indian invasions by expanding westward from coastal population centers, gaining access to natural resources and fur trading opportunities, securing the frontiers, and building a defensive line of fortifications, while also sending missionaries to build alliances and seek converts. American Indians sought to hold onto tribal lands by stopping British expansion, maintaining trade with Europeans for firearms, ammunition, cooking utensils, and textiles, and choosing alliance or neutrality according to what seemed most advantageous at a given time. From 1749 to 1763, the conflict unfolded fort by fort: French claims and mission forts in the Ohio Valley were followed by the building of Forts Presque Isle, Le Boeuf, and Duquesne; George Washington demanded that the French leave the Ohio Valley, then built and surrendered Fort Necessity; British defeats came near Fort Duquesne, at Fort Bull, and at Oswego, while William Johnson won at Lake George and began Fort William Henry; French and Indians attacked German Flats, and Montcalm destroyed Fort William Henry; later British forces took Louisbourg, Frontenac, Fort Duquesne, Fort Niagara, Quebec, Carillon, and St. Frederic, rebuilt Fort Ontario, began Fort Pitt and Fort Crown Point, and forced the surrender of Montreal after the French failed to retake Quebec; in 1763, the Treaty of Paris officially ended hostilities between the French and British and determined the fate of North America.