During this interval Burgoyne actively exerted himself in opening a passage from Fort Anne to Fort Edward. But, notwithstanding the diligence with which the whole army engaged in the work, their progress was exceedingly slow, so formidable were the obstacles which nature as well as art had thrown in their way. Besides having to remove the fallen trees with which the Americans had obstructed the roads they had no less than forty bridges to construct and many others to repair; one of these was entirely of log work, over a morass two miles wide. In short the British encountered so many impediments in measuring this inconsiderable space that it was found impossible to reach the banks of the Hudson near Fort Edward until the 30th of July (1777). The Americans, either because they were too feeble to oppose the enemy or that Fort Edward was no better than a ruin, not susceptible of defense, or finally because they were apprehensive that Colonel St. Leger, after the reduction of Fort Stanwix, might descend by the left bank of the Mohawk to the Hudson and thus cut off their retreat, retired lower down to Stillwater where they threw up entrenchments. At the same time they evacuated Fort George, having previously burned their boats upon the lake, and in various ways obstructed the road to Fort Edward. Burgoyne might have reached Fort Edward much more readily by way of Lake George, but he had judged it best to pursue the panic-stricken Americans, and, despite the difficulties of the route, not to throw any discouragements in the way of his troops by a retrograde movement. At Fort Edward General Burgoyne again found it necessary to pause in his career, for his carriages, which in the hurry had been made of unseasoned wood, were much broken down and needed to be repaired. From the unavoidable difficulties of the case not more than one-third of the draught horses contracted for in Canada had arrived, and General Schuyler had been careful to remove almost all the horses and draught cattle of the country out of his way. Boats for the navigation of the Hudson, provisions, stores, artillery, and other necessaries for the army were all to be brought from Fort George, and although that place was only nine or ten miles from Fort Edward, yet such was the condition of the roads, rendered nearly impassable by the great quantities of rain that had fallen, that the labor of transporting necessaries was incredible. Burgoyne had collected about 100 oxen, but it was often necessary to employ ten or twelve of them in transporting a single boat. With his utmost exertions he had on the 15th of August conveyed only twelve boats into the Hudson and provisions for the army for four days in advance. Matters began to assume a very serious aspect indeed, and as the further he removed from the lakes the more difficult it became to get supplies from that quarter, Burgoyne saw clearly that he must look elsewhere for sustenance for his army.