In sending two thousand five hundred cavalry to Acqui to watch Suchet, Melas committed an error that probably lost him the battle. There was little or no excuse for this error; for Suchet was so far away that he could not possibly arrive at Marengo in time to take part in the battle. Had Melas kept this cavalry force on the battle-field, and thrown it vigorously against the French as they fell back towards San Giuliano, he would undoubtedly have won the battle. It was the failure of the Austrians to pursue the French promptly that enabled Bonaparte to rally the scattered remnants of his defeated forces near San Giuliano. Says Colonel Hart:-- "When a great battle is imminent, it is unwise for a commander to detach any part of the force available, unless he is very confident of victory. There are many examples in history of misfortune, or misfortune narrowly escaped, in consequence of doing so. Melas would, in all probability, have made perfectly certain of the victory at Marengo, if he had not unnecessarily detached 2500 cavalry to arrest the march of Suchet, who was at too great a distance to be taken into consideration. Napoleon himself at Marengo, although ultimately victorious, was as nearly as possible defeated because he detached Desaix to reconnoitre towards Rivalta; indeed, he was at first defeated, but the return of Desaix restored the battle." It is here worthy of notice that while Melas was sending away this detachment of two thousand five hundred men, Bonaparte was making every effort to hasten the return of the six thousand men under Desaix. At the sound of the first cannon-shot at Marengo, Desaix faced about his command and hurried forward to aid Bonaparte. It was fortunate that the First Consul had Desaix for a lieutenant at Marengo. Had Grouchy marched to the sound of the cannon at Waterloo, and supported his chief as loyally as did Desaix at Marengo, Napoleon might never have fallen. If Suchet, who was at Acqui with the remnants of the Army of Italy, numbering about twenty thousand men, had pushed on vigorously towards Marengo, and had arrived there on the morning of the 14th of June, the battle would have been decided in favor of the French early in the day. Such a movement would have given Bonaparte an overwhelming superiority in numbers, and would probably have resulted in the destruction or capture of the whole army of Melas.