<P> The French imperial government now looked to a diplomatic success to stifle demands for a return to either a republic or a Bourbon monarchy . A war with Prussia and resulting territorial gains in the Rhineland and later Luxembourg and Belgium seemed the best hope to unite the French nation behind the Bonapartist dynasty . With the resulting prestige from a successful war, Napoleon III could then safely suppress any lingering republican or revolutionary sentiment behind reactionary nationalism and return France to the center of European politics . </P> <P> Prussia in turn was also beset with problems . While revolutionary fervour was far more muted than in France, Prussia had in 1866 acquired millions of new citizens as a result of the Austro - Prussian War, which was also a civil war among German states . The remaining German kingdoms and principalities maintained a steadfastly parochial attitude towards Prussia and German unification . The German princes insisted upon their independence and balked at any attempt to create a federal state that would be dominated by Berlin . Their suspicions were heightened by Prussia's quick victory and subsequent annexations . Before the war, only some Germans, inspired by the recent unification of Italy, accepted and supported what the princes began to realise, that Germany must unite in order to preserve the fruit of an eventual victory . </P> <P> Bismarck had an entirely different view after the war in 1866: he was interested only in strengthening Prussia through the eyes of a staunch realist . Uniting Germany appeared immaterial to him unless it improved Prussia's position . Bismarck had mentioned before the war the possibility of ceding territory along the Rhine to France, and Napoleon III, urged by his representatives in France, used these casual references by Bismarck to press for more of the territory that Prussia had received from Austria . These discussions, leaked by Bismarck to the German states in the south, turned former enemies into allies almost overnight, receiving not only written guarantees but armies that would be under the control of Prussia . </P> <P> Diplomatically and militarily, Napoleon III looked for support from Austria, Denmark, Bavaria, Baden, and Württemberg, as all had recently lost wars against Prussia . However, Napoleon III failed to secure revanchist alliances from these states . Denmark had twice fought Prussia during the First and Second Wars of Schleswig (a stalemate in the 1848--50, and a defeat in 1864 against a confederation of North German states and Austria under the leadership of Prussia), and was unwilling to confront Prussia again . As part of the settlement of the Austro - Prussian War in 1866, secret treaties of mutual defense were signed between Prussia and Bavaria, Baden, and Württemberg . What made them especially significant was that not only were they secret, giving Napoleon III a false sense of security, but Bismarck had used Napoleon III's earlier demand of territory along the Rhine to drive the southern German states into his arms . By these treaties, Prussia would defend all of the southern German states with its military power as long as their states joined the Northern Confederation in defense of Prussia . It was a bargain that would gravely threaten the French empereur and his designs on restoring French pride . </P>

The immediate cause of the franco-prussian war was a struggle over