[6] Elected republican deputy for Paris in 1869, he protested against the declaration of war with Germany, and on 6 September 1870 was appointed prefect of the Seine by the Government of National Defense.

He reorganized the committee of public education (law of 27 February 1880) and proposed a regulation for the conferring of university degrees, which, though rejected, aroused violent polemics because the 7th article took away from the unauthorized religious orders the right to teach.

He finally succeeded in passing his eponymous laws of 16 June 1881 and 28 March 1882, which made primary education in France free, non-clerical (laïque) and mandatory.

In higher education, the number of professors called the "Republic's black hussars" (French: hussards noirs de la République) because of their Republican support, doubled under his ministry.

[7] After the military defeat of France by Prussia in 1870, Ferry formed the idea of acquiring a great colonial empire, principally for the sake of economic exploitation.

The excitement caused in Paris by the sudden retreat of the French troops from Lạng Sơn during this war led to the Tonkin Affair: his violent denunciation by Clemenceau and other radicals, and his downfall on 30 March 1885.

Although the treaty of peace with the Chinese Empire (9 June 1885), in which the Qing dynasty ceded suzerainty of Annam and Tonkin to France, was the work of his ministry, he would never again serve as premier.

A committed republican, Ferry undertook a wide-scale "purge" by dismissing many known monarchists from top positions in the magistrature, army, and civil and diplomatic service.

Most French politicians in the middle and right saw it as a sacred duty to one day lead France again against Germany to reclaim Alsace-Lorraine, and avenge the awful defeat of 1870.

But he also suggested Franco-German cooperation on the imperial front against the British Empire, thus hoping to create a wedge between the two Western European great powers.

As for Fashoda, while it was a confrontation, it led to Britain and France eventually discussing their rival colonial goals, and agreeing to support each other's sphere of influence – the first step to the Entente Cordiale between the countries in 1904.

After the resignation of Jules Grévy (2 December 1887), he was a candidate for the presidency of the republic, but the radicals refused to support him, and he withdrew in favor of Sadi Carnot.