General Greene was not content with providing against invasion from the northeast, but also turned his attention to the section lying to the south of Fort Greene. He saw the necessity of erecting intrenchments along the high land extending from Fulton Avenue southerly to the old Gowanus Road, at the creek which made up from the bay where Freeck's mill stood. This spot can be easily fixed. Many remember the old mill pond and the bridge across the creek at Butler Street, near where Bond Street has been extended. Another small redoubt, which stood like a warning sentinel, was erected a short distance west of the fort, about where DeKalb Avenue now intersects Hudson Avenue. South Brooklyn was not forgotten. At that time the section bounded by Smith and Clinton streets on the east, and Degraw and Third Place on the north, was high ground, and from its owner's name was called Bergen Hill. This prominence commanded a view of the East River and Gowanus Bay. Here Greene erected a redoubt, on which he mounted several guns. In later times, when the hill was removed, to give place to streets and palatial residences, the remains of soldiers buried during the Revolutionary War were taken up. A fort was also built on Cobble Hill, which was nick-named "Corkscrew Fort." This hill was on the spot where since has been erected the Athenæum, corner of Clinton and Atlantic streets. All these works were effectively built and evinced great military and engineering skill. English officers at the time of the evacuation referred to their strength of material and advantageous location. It would appear that Greene and his assistants thoroughly familiarized themselves with the topography of the country, and made military provision accordingly. A British officer, in his experiences published during the war, expressed in strong terms his surprise that the Americans should retreat from bastions so impregnable. Hitherto all had been preparation. The storm clouds had been gathering, and were soon to break with unwonted fury. A great Revolutionary battle was to be fought on the virgin soil of Long Island, and was to result disastrously.