The allied plan sinned against one of the elementary rules of strategy; it exposed a large force to a blow from the rear, namely, from Switzerland. The importance of this immensely strong central position early attracted Bonaparte's attention. On the 17th of March he called his secretary, Bourrienne (so the latter states), and lay down with him on a map of Piedmont: then, placing pins tipped, some with red, others with black wax, so as to denote the positions of the troops, he asked him to guess where the French would beat their foes: "How the devil should I know?" said Bourrienne. "Why, look here, you fool," said the First Consul: "Melas is at Alessandria with his headquarters. There he will remain until Genoa surrenders. He has at Alessandria his magazines, his hospitals, his artillery, his reserves. Crossing the Alps here (at the Great St. Bernard), I shall fall upon Melas, cut off his communications with Austria, and meet him here in the plains of the River Scrivia at San Giuliano." I quote this passage as showing how readily such stories of ready-made plans gain credence, until they come to be tested by Napoleon's correspondence. There we find no strategic soothsaying, but only a close watching of events as they develop day by day. In March and April he kept urging on Moreau the need of an early advance, while he considered the advantages offered by the St. Gotthard, Simplon, and Great St. Bernard passes for his own army. On April 27th he decided against the first (except for a detachment), because Moreau's advance was too slow to safeguard his rear on that route. He now preferred the Great St. Bernard, but still doubted whether, after crossing, he should make for Milan, or strike at Masséna's besiegers, in case that general should be very hard pressed. Like all great commanders, he started with a general plan, but he arranged the details as the situation required. In his letter of May 19th, he poured scorn on Parisian editors who said he prophesied that in a month he would be at Milan. "That is not in my character. Very often I do _not_ say what I know: but never do I say what will be."