The plates of lead along the Ohio had very little effect in retarding the Ohio Company of Virginians, and Celoron had hardly left the Ohio Valley when Christopher Gist entered it to pick out and mark the boundaries of the Ohio Company's grant of land. This was in 1750. The Quebec Government, too, acted. If leaden plates would not hold the Ohio, then forts well guarded and manned would accomplish the end sought; and English spies on watch at Fort Oswego now saw a strange flotilla crossing Lake Ontario and knew something extraordinary was in the air. It was Marin's party on its way to fortify Celoron's route by building a chain of posts from Fort Niagara to the present site of Pittsburg at the junction of the Allegheny and Monongahela rivers. After a rest at Niagara the fort-building party proceeded along Lake Erie to Presqu' Isle, now Erie, Pennsylvania. There they built Fort Presqu' Isle; at Watertown Fort La Boeuf was erected and Fort Machault at Franklin on the Allegheny, and Fort Duquesne at the junction of the Allegheny and Monongahela. All this between 1752 and 1754, despite the message sent by Governor Dinwiddie of Virginia by the hand of Major Washington requesting that the French withdraw from the Ohio Valley. In the latter year Washington marched westward to support the party of Virginian fort-builders who had been sent to fortify the strategic position on the Ohio, but was forced to capitulate by the French army, which drove back the English and on their beginnings erected Fort Duquesne. The line of forts from Quebec to Fort Duquesne was now complete, and of them Fort Niagara was the key. To wrest from the French this western empire it was necessary to strike Fort Niagara, but, with the rare lack of foresight characteristic of the government headed by the impossible Newcastle, the great campaign of 1755 was as poorly conceived as it was executed. It was composed of three spectacular advances on this curling line of French forts that hemmed in the colonies; one army, under Sir William Johnson, should attack the forts on Lakes George and Champlain; Governor Shirley of Massachusetts should leap at Fort Niagara, and General Braddock, formerly commander of Gibraltar, should lead an army from Virginia across the mountains upon Fort Duquesne, after capturing which he should then join forces with Shirley for the conquest of Niagara if that post had not been previously reduced.