Melas was still west of Alessandria, at a distance of two days' march. Bonaparte, after leaving Milan for headquarters, remained in the rear, gathering and ordering the advancing army, but giving no sign, by a personal appearance on the front, until all was in readiness, of where the decision would be taken. It was a maxim ever on his lips to prepare for a decisive action by bringing in every available man; no one could tell when the result might turn on the presence of a few men more or less. In this instance he was apparently untrue to his own principle; for no less than twenty-three thousand men had been sent so far out of reach--some to cut off all chance of Austrian escape to the north, east, and south, and some for various other purposes--that he now had only thirty-four thousand men available. His over-confidence was in a sense justified by the enemy's mistakes, but it came near to costing dearly. It went so far that Loison, with six thousand soldiers more, was left behind at Piacenza. By the twelfth Melas had joined Ott at Alessandria, which, in view of Bonaparte's grand strategy, was inevitable. Desaix, in obedience to the urgent summons he had received from the First Consul, had finally reached the French headquarters at Stradella on the eleventh, and was immediately put in command of one of the three corps, his colleagues being Victor and Lannes. The flat land about Tortona and Alessandria is watered by two small rivers, the Scrivia and the Bormida, which flow parallel to each other northward toward the Po. Irrigating canals and minor tributary streams, all bordered by pollard willows and other low trees, separate the fields, which are themselves planted with orchards, or yield rich crops of cereals. It was customary for Bonaparte to select an open plain for his battles, if possible. He could then, without fear of being hampered, use his favorite arm, the artillery, which he frequently massed with terrible effect on the wings, while his effective cavalry were sent in repeated onsets to break his enemy's center, and deliver the opposing ranks in broken masses to the musket-fire and bayonet charge of his infantry. Such fields were, of course, numerous between Tortona on the Scrivia and Alessandria on the Tanaro just west of its confluence with the Bormida. The best was near the great highway which, coming from the east, connects these two towns, and goes on, due westward, by Asti to Turin. Two roads of importance lead southerly, one from each town, to Novi, where they unite, and then proceed to Genoa. On the northern side of the triangle thus formed, and only three miles eastward from Alessandria, lies the hamlet of Marengo, where Victor was posted on June thirteenth, awaiting the attack of Melas when he should sally from the fortress. Lannes was about three miles behind at San Giuliano. Desaix had been sent southward toward Novi, lest Melas should swerve in that direction to try a flank movement.