In August, 1611, Sir Thomas Gates, returning to assume the command of the colony, pushed vigorously the work upon the new settlement.[90] Dale was sent up the river with no less than three hundred men, with directions to construct houses and fortifications. The settlers, working with new life and vigor in the more wholesome air of the upper James, soon rendered the place almost impregnable to attack from the Indians. They cut a ditch across the narrow neck of the peninsula, and fortified it with high palisades. To prevent a sudden raid by the savages in canoes from the other shore, five strong block houses were built at intervals along the river bank. Behind these defenses were erected a number of substantial houses, with foundations of brick and frame superstructures. Soon a town of three streets had been completed, more commodious and far more healthful than Jamestown.[91] When this work had been completed, Dale led a force of men across to the south bank of the river and took possession of the entire peninsula lying between the Appomattox and the James. An Indian settlement just below Turkey Island bend was attacked and destroyed, and the savages driven away. The English built a palisade over two miles long and reinforced at intervals with forts and block houses, from the James at Henrico to the falls of the Appomattox. These fortifications secured from the attacks of the savages "many miles of champion and woodland", and made it possible for the English to lay out in safety several new plantations or hundreds. Dale named the place Bermuda, "by reason of the strength of the situation". Here, for the first time, something like prosperity came to the colony. Although the "sicknesse" was not entirely eliminated even at Henrico, the percentage of mortality was greatly reduced. Soon there were in Virginia several hundred persons that had lived through the fatal months of June, July and August and were thoroughly "seasoned" or immune to the native disorders. Not until 1618, when the settlers, in their greed for land suitable for the cultivation of tobacco, deserted their homes on the upper James for the marshy ground of the lower country, and new, unacclimated persons began arriving in great numbers, did the pestilence again assume its former proportions.