In the afternoon all was changed. The Austrians were scattered; they stretched from Marengo to San Giuliano. Moreover, they were marching carelessly and had no expectation that Bonaparte would attack them. Meanwhile, Desaix had returned, and Bonaparte's forces had rallied behind the hillocks near San Giuliano. In a short time Bonaparte overthrew the advance under Zach, then proceeding westward, gathering momentum and strength as a result of his first success, he outnumbered and crushed in succession the several Austrian organizations. Thus the Austrians were defeated in detail in the afternoon as the French had been defeated in the morning. Here again is seen the necessity of outnumbering an enemy at the vital point of the battle-field. Courage and heroism on the field of battle are of little avail, unless a commander concentrates his forces and outnumbers his adversary at the decisive point. The brain of the commanding general is the birthplace of victory. In this battle the genius of Bonaparte is seen, not in the knowledge he displayed of his adversary's doings, for Bonaparte was completely surprised at Marengo; not in the arrangement of his forces, for that could hardly have been worse; not in any deeds of surpassing courage, for no one could excel the heroism of Lannes on that battle-field; but in his complete mastery of the situation,--in the fact that, amidst turmoil, ruin, and death, he saw just when and where and how the blow should be struck to change disaster into victory. This was the merit of Bonaparte at Marengo. On that field he was a great tactical captain. While the storm of battle was at its height, and the dying and the dead were around him, he was cool, clear-headed, and vigilant. While disaster was staring him in the face, he saw the vulnerable spot in the formation of his adversary's forces, and by massing troops there, crushed and overwhelmed them. In this campaign Bonaparte was fortunate in having a Masséna at Genoa, a Suchet on the Var, and a Lannes at Montebello and at Marengo. He was fortunate, too, in having a Desaix near at hand, who dared march to the sound of the cannon, and who counselled hope when he might have counselled despair.