Behind the town extended a plain rather more than half a mile wide; and beyond that rose hills of light sand--enlarged editions of the dunes that ran along the shore north and south of Vera Cruz--which gradually increased in height until some of them, two or three miles inland, reached an elevation of perhaps three hundred feet. Then came dense forests, cut here and there by a road and occasionally diversified with oases of cultivated land, richly scented by tropical fruits and flowers. To the southwest of the city lay a series of ponds and marshes, drained by a small stream that passed near the wall; and this creek, supplemented by cisterns and an underground aqueduct, provided the town with water. In the opposite direction, on a reef named the Gallega--distant nearly three quarters of a mile from Fort Concepción--rose the fortress of Ulúa, built of soft coral stone, faced with granite, in the most scientific manner, and large enough to accommodate 2500 men.[22.4] Water batteries lay wherever it seemed possible to effect a landing, and tremendous walls, enfeebled by no casemates, towered to a height of about sixty feet.[22.9] At the beginning of March, 1846, Mora y Villamil, the highest engineer officer in the Mexican army and at this time comandante general of Vera Cruz, feared that on account of Slidell's departure the Americans might suddenly attack him. Aided by Lieutenant Colonel Manuel Robles, a skilful and active subordinate, he drew up detailed plans for repairing the crumbling fortifications of the city and castle, and these were approved by the government; but the lack of money prevented the full execution of them. In October the captain of a British frigate warned the new comandante general that an American attack was imminent; and at about the same time Santa Anna, while bitterly reproaching the government for its neglect of the town and pointing out what needed to be done, charged him to make the "strong buildings" a second and a third line of defence in case of attack, and then perish, if necessary, under the ruins of the city; but again the want of funds vetoed adequate preparations. On the other hand, unpaid soldiers paid themselves by stealing powder and selling it.[22.9]