At Detroit, Mackinac, and Sault Ste. Marie the French continued to hold possession of the Great Lakes and the country to the west and south. Their communications, then, between the West and Quebec were established, but between the great valleys of the St. Lawrence and the Mississippi, over which they claimed exclusive rights, there was another valley which became of importance in the execution of their scheme of continental dominion. In the years succeeding the treaty of Aix-la-Chapelle the English colonists awakened to the importance of the valley of the Ohio, and adventurous frontiersmen of Virginia and Pennsylvania were already forcing their way into its wilderness, when France's ambition barred the way to their further progress. That astute Canadian, Governor La Galissonniere, in 1749, recognised the importance of the Ohio in relation to the Illinois and Mississippi, and sent Celoron, a captain in the French service, to claim possession of the valley of the former river and its tributaries. This officer made a long and enterprising journey, in the course of which he affixed at different points the arms of France to trees, and buried leaden plates bearing the inscription, that they were memorials of the "renewal of the possession of the Ohio and all its affluents" originally established by arms and treaties, particularly those of Ryswick, Utrecht, and Aix-la-Chapelle. Under the instructions of Governor Duquesne, who possessed all the sagacity of La Galissonniere, forts were established at Presqu'ile (Erie) and on French Creek, a tributary of the Alleghany. Virginians saw with dismay the entrance {224} of the French into a region on which they were now casting a longing eye. Their government had secured from the Iroquois a doubtful deed which gave them, as they urged, a title to the Great West, and a company was even formed to occupy the Ohio. In 1754 the English commenced the construction of a fort at the forks of the Ohio, but it was easily captured by Contrecoeur, who completed and renamed it in honour of the Governor of Canada, Duquesne. Washington, who now first appears in American history, was defeated by Chevalier de Villiers at Fort Necessity, a mere intrenchment at Great Meadows, and the French held entire possession of the Ohio valley, where no English trader or pioneer dared show himself. By 1755 the French dominion was complete from the Ohio to the Illinois, and from the Great Lakes to the Gulf of Mexico, so far as a slender line of communication by means of widely separated posts and settlements could make it so. On the St. Joseph, the Maumee, the Wabash, and the Illinois, there were small forts. Fort Chartres in the Illinois country was the only post of any thorough construction. At Cahokia, opposite the modern city of St. Louis, and at Kaskaskia, at the junction of the river of that name with the Mississippi, there were small and relatively prosperous French villages.