The Republican Union was a French parliamentary group in the Chamber of Deputies of France

Chamber of Deputies of France

Chamber of Deputies was the name given to several parliamentary bodies in France in the nineteenth and twentieth centuries:* 1814–1848 during the Bourbon Restoration and the July Monarchy, the Chamber of Deputies was the Lower chamber of the French Parliament, elected by census suffrage.*...

 during the French Third Republic

French Third Republic

The French Third Republic was the republican government of France from 1870, when the Second French Empire collapsed due to the French defeat in the Franco-Prussian War, to 1940, when France was overrun by Nazi Germany during World War II, resulting in the German and Italian occupations of France...

 founded on March 25, 1911 which united the left-wing of the Progressive Republicans

Republican Federation

The Republican Federation was the largest conservative party during the French Third Republic, gathering together the liberal Orleanists rallied to the Republic. Founded in November 1903, it rivalized with the more secular and centrist Alliance démocratique...

, the most conservative group in the Chamber. The founders of the UR opposed the Progressive's rapprochement with the nationalist or Rallied (ralliée) right.

Most went on to found the Democratic Left, which became one of the first groups of the Democratic Republican Alliance

Democratic Republican Alliance

The Democratic Republican Alliance was a French political party created in 1901 by followers of Léon Gambetta, such as Raymond Poincaré who would be president of the Council in the 1920s...

(ARD).