Each of these men influenced, to varying degrees, the outcome of the Franco-Prussian War.  Their contributions and talents varied, but each had a part to play in the conflict.

Otto von Bismarck (Herwig, p.118)

Otto von Bismarck was one of the most influential men in German history.  He was an ultra-conservative, pro-monarch, Prussian nationalist.  Born into an old, aristocratic family, he believed in the rights of the nobility and the monarchy.  Bismarck would go to any length to further the interests of the state.  He wanted Prussia (and later Germany), to be a strong, powerful nation.  Bismarck was appointed Premier of Prussia in 1862, and immediately set out to expand Prussian power.  After defeating the Danes and the Austrians, Bismarck turned his attention to France.  He used the issue of the candidature of a Hohenzollern to the throne of Spain as a means of deliberately provoking the French into war.  After the defeat of France, Bismarck was able to consolidate the German states into the German Empire.  He is known as the father of the German Empire and was its first chancellor.  At the height of his power, Bismarck had almost complete control of German foreign and domestic affairs.  Otto von Bismarck remains one of the most influential men in German history.

William I was King of Prussia from 1861-1888, and Emperor of Germany from 1871-1888.  He was essentially a conservative ruler who believed in the privilege of the nobility and the divine right of the monarchy.  William's primary objective as king was to expand Prussia's power by revitalizing and reforming her military.  William appointed the brilliant Otto von Bismarck as his Premier in 1862 to further this goal.  Bismarck managed to gain William's complete confidence and was soon directing Prussia's domestic and foreign affairs.  As Bismarck was the more capable and politically acute of the two, William generally conceded to him when they differed in opinion.  Thus, although William's reign was significant in German history, most of the victories and achievements obtained were due to Bismarck's genius rather then William's.  William can be credited with having promoted the great rise in Prussian militarism which ultimately led to the unification of the German states into the German Empire. (19)

Bazaine was a French army officer who was promoted to Supreme Commander by Emperor Napoleon III.  Bazaine was ill-prepared to direct such a campaign and made many grievous mistakes.  His greatest blunder was to allow the Prussian army to surround him at Metz which led to the fateful disaster for the French army at Sedan.  Bazaine was forced to resign his commission when it was discovered that he had been involved in some sort of "diplomatic intrigue" with the Prussians.  Bazaine's military career was effectively ended when he was convicted of treason in connection with events of the Franco-Prussian War. (19)

Thiers was a moderately liberal French politician who supported Louis Napoleon as president of the French Republic. When Louis Napoleon seized control of the government in 1851, Thiers became an outspoken critic of the action and so was arrested and exiled.  Thiers opposed French involvement in the Franco-Prussian War and when France was defeated in 1871, he was made President of the new Republic.  Thiers met with Bismarck to draw up the Peace of Frankfurt and later ordered French troops to suppress the Commune of Paris. (19)

Prince Leopold Hohenzollern was the son of Prince Charles Anthony, a member of the Catholic branch of the House of Hohenzollern.  Prince Leopold was married to the daughter of the ex-King of Portugal, and was related by marriage to the Bonaparte family of France.  These family connections, in addition to his Catholicism, led many in Spain to consider him a likely candidate for the Spanish throne.  The controversy that his proposed candidacy evoked was a major cause of the hostilities that led to the outbreak of the Franco-Prussian war. (33)