At a founding congress organized in the Allier from 8 to 10 June 2019, Alternative Libertaire (AL) and the Coordination of Anarchist Groups (CGA) enacted their fusion, the result of a year of discussions.

UCL retains red and black colors, symbolic of communism and anarchism, as well as the Libertarian Alternative newspaper, which did not change its name.

[1] In the same month, UCL claimed about forty local groups linked to the organization and more than five hundred members.

[2] Many were trade unionists, from unions such as Solidaires Unitaires Démocratiques or the General Confederation of Labour and associations.

[1] The Libertarian Communist Union supported the Yellow vests movement since its inception.