Napoleon estimated his position better than his people. Despite his victories, his situation was one of danger and difficulty. The army had suffered severely in its brief campaign, and the Austrians were still in possession of the Quadrilateral, a square of powerful fortresses which he might seek in vain to reduce. And a threat of serious trouble had arisen in Germany. The victorious career of a new Napoleon in Italy was alarming. It was not easy to forget the past. The German powers, though they had declined to come to the aid of Austria, were armed and ready, and at any moment might begin a hostile movement upon the Rhine. [=A Meeting of the Emperors and Treaty of Peace=] Napoleon, wise enough to secure what he had won, without hazarding its loss, arranged a meeting with the Austrian emperor, whom he found quite as ready for peace. The terms of the truce arranged between them were that Austria should abandon Lombardy to the line of the Mincio, almost its eastern boundary, and that Italy should form a confederacy under the presidency of the pope. In the treaty subsequently made only the first of these conditions was maintained, Lombardy passing to the king of Sardinia. He received also the small states of Central Italy, whose tyrants had fled, ceding to Napoleon, as a reward for his assistance, the realm of Savoy and the city and territory of Nice. Napoleon had now reached the summit of his career. In the succeeding years the French were to learn that they had put their faith in a hollow emblem of glory, and Napoleon to lose the prestige he had gained at Magenta and Solferino. His first serious mistake was when he yielded to the voice of ambition, and, taking advantage of the occupation of the Americans in their civil war, sent an army to invade Mexico. [=The Invasion of Mexico=] The ostensible purpose of this invasion was to collect a debt which the Mexicans had refused to pay, and Great Britain and Spain were induced to take part in the expedition. But their forces were withdrawn when they found that Napoleon had other purposes in view, and his army was left to fight its battles alone. After some sanguinary engagements the Mexican army was broken into a series of guerilla bands, incapable of facing his well-drilled troops, and Napoleon proceeded to reorganize Mexico as an empire, placing the Archduke Maximilian of Austria on the throne. All went well while the people of the United States were fighting for their national union, but when their war was over the ambitious French emperor was soon taught that he had committed a serious error. He was given plainly to understand that the French troops could only be kept in Mexico at the cost of a war with the United States, and he found it convenient to withdraw them early in 1867. They had no sooner gone than the Mexicans were in arms against Maximilian, and his rash determination to remain quickly led to his capture and execution as a usurper. [=Napoleon Loses Prestige in France=]