Formed in the early years of the French Third Republic, the Republican Union led by Léon Gambetta was strongly opposed to the Treaty of Frankfurt as much understanding to the Paris Commune, repressed by the moderate Adolphe Thiers.
The party's electoral lists also included notable activists and intellectuals like Louis Blanc (elected with 216,000 votes),[1] Victor Hugo, Giuseppe Garibaldi, Edgar Quinet, Pierre Waldeck-Rousseau, Émile Littré, Charles Floquet, Georges Clemenceau, Arthur Ranc and Gustave Courbet.
Initially on the extreme left of the Parliament of France, the group became close to the Opportunist Republicans of Jules Ferry in the late 1870s, causing a split of the far-left radicals led by Clemenceu.
After the 1885 legislative election, the Republican Union's popularity decreased while the Opportunists to their right increased their votes.
However, changes in the political system led to a need for a big party of all liberals and when the Democratic Republican Alliance was created in 1901 the Opportunists and the Progressive Union merged into it.