Soon after Sadowa the Emperor tried to obtain territorial compensation from Prussia. He wished, in return for recognition of Prussia's new position and of the projected union of North and South Germany minus Austria, to obtain the cession of territories on the left bank of the Rhine, or an alliance for the conquest and annexation of Belgium to France. Such schemes having failed, Napoleon tried next to satisfy French jingoism by the acquisition of the Duchy of Luxembourg. This move resulted only in securing the evacuation by its Prussian garrison of the Luxembourg fortress and the neutralization of the duchy. From that time on, tension increased between France and Prussia. Bismarck was, indeed, more anxious for war than Napoleon. He suspected the weakness of the French Empire, he despised its leaders, he realized the advance in military efficiency of his own country, and his aim was unswerving to establish a Prussianized German Empire at the cost, if possible, of the downfall of France. As a matter of fact, France, as now, was far from being permeated with militarism and, a few months before the war in 1870, the military budget was actually reduced.
The occasion for a dispute arrived with the suggested candidacy of Leopold of Hohenzollern-Sigmaringen, a German prince related to the King of Prussia, to the crown of Spain. As early as 1868, intrigues had begun to put a Prussian on the Spanish throne, but Napoleon had not as yet been disturbed. It was not until 1870 that he took the matter seriously. In July, Prince Leopold accepted the crown, egged on by Bismarck, and with the fiction of the approval of King William as head of the Hohenzollerns, as distinguished from his position as King of Prussia.
At that time the French Emperor was in precarious health and scarcely in full control of his powers. The French people at large were pacifically inclined and would have asked for nothing better than to remain at home instead of fighting about a foreigner's candidacy to an alien throne. But, unfortunately, the Empress Eugénie was for war. The Government, too, was in the hands of second-rate and hesitating diplomats. Emile Ollivier, the chief of the Cabinet, was an orator more than a statesman, and the Minister of Foreign Affairs, the duc de Gramont, was a conceited mediocrity more and more involved in his own mistakes. In consequence, the attitude of the Government was not so much deliberate desire for war as provocative bluster, of which Bismarck was quick to take advantage. The Cabinet was egged on by Eugénie's adherents, the militants, who had been looking for an insult since Sadowa, and by obstreperous journalists and noisy boulevard mobs, whose manifestations were unfortunately taken, even by the Corps législatif, for the voice of France.
In consequence, blunder after blunder was made. The ministers worked at cross-purposes, without due consultation and without consideration of the effect of their actions on an inflamed public opinion or on prospective European alliances. Stated in terms of diplomatic procedure, the aim of the French Cabinet was to humiliate Prussia by forcing its Government to acknowledge a retreat. King William was not seeking war and was probably willing to make honorable concessions. Bismarck, on the contrary, desired war, if it could be under favorable diplomatic auspices, and the Hohenzollern candidacy was a direct provocation. He wanted France to seem the aggressor, in view of the effect both on neutral Europe, and particularly on the South German States, which he wished to draw into alliance under the menace of French attack.
The French Ambassador to the King of Prussia, Benedetti, was instructed to demand the withdrawal of Prince Leopold's candidacy. This demand followed a very arrogant statement to the Corps législatif, on July 6, by the duc de Gramont. The assumption was that Prince Leopold's presence on the Spanish throne would be dangerous to the honor and interests of France, by exposing the country on two sides to Prussian influence. King William was, on the whole, willing to make a concession to avoid international complications, but he obviously wished not to appear to act under pressure. M. Benedetti went to Ems and, on July 9, he laid the French demands before the King. After long-drawn-out discussion the French Government asked for a categorical reply by July 12. On that day the father of Prince Leopold, Prince Antony of Hohenzollern, in a telegram to Spain, formally withdrew his son's name. The King had planned to give his consent to this apparently spontaneous action on the part of the candidate's family, when officially informed. Thus France would obtain its ends and the King himself would not be involved.
Unfortunately the thoughtlessness of the head of the French Ministry spoiled everything. Instead of waiting a day for the King's ratification, Emile Ollivier, desirous also of peace, hastened to make public the telegram from the Prince of Hohenzollern. Thereupon the leaders of the war party in the Corps législatif at once pointed out that the telegram was not accompanied by the signature of the Prussian monarch, declared that the Cabinet had been outwitted, and clamored for definite guarantees. Stung by the charge of inefficiency, the would-be statesman Gramont immediately accentuated his stipulations and demanded that the King of Prussia guarantee not to support in future the candidacy of a Hohenzollern to the Spanish throne.
Matters were rapidly reaching an impasse, and Bismarck was correspondingly elated, because France was appearing to Europe a trouble-maker. The duc de Gramont and Emile Ollivier committed the error of dictating a letter to the Prussian Ambassador for him to transmit to the King, to be in turn sent back as his reply. King William was offended by this high-handed procedure. He had already told comte Benedetti at Ems that a satisfactory letter was on its way from Prince Antony and had promised him another interview upon its arrival. After receiving the dispatch from his ambassador at Paris communicating Gramont's formulas, he sent word to Benedetti that Prince Leopold was no longer a candidate and that the incident was closed. Nor was the King willing to grant Benedetti's urgent requests for an interview (July 13).
The King and the French Ambassador had remained perfectly courteous, and the next day, at the railway station, they took leave of each other with marks of respect. Things were not yet hopeless, until Bismarck, by a trick of which he afterwards bragged, caused a dispatch to be published implying that Benedetti had been so persistent in pushing his demands that King William had been obliged to snub him. The French were led to believe that their representative had been insulted, and neutrals sided with Prussia as the aggrieved party. After deliberation the French Ministry decided on war and the decision was blindly ratified by the Corps législatif on July 15. At this meeting Emile Ollivier made his famous remark that the Ministry accepted responsibility for the war with a "clear conscience." His actual words, "le cœur léger," seemed, however, to imply "with a light heart", and thereafter weighed heavily against him in the minds of Frenchmen.