He was involved in a series of controversies during this time, due to his rejection of anarcho-syndicalism and recognition of minority nationalities in Spain, over which he was forced to resign his posts.
By the time of the Second Spanish Republic, he had left the syndicalist movement and become a Catalan nationalist, serving in the Barcelona City Council as a member of Acció Catalana Republicana [ca].
[1] In January 1913, the government of Álvaro de Figueroa granted an amnesty for trade union organisers and the CNT began to return to public activity.
[4] Andreu represented the paper at an International Peace Congress in Ferrol, where he met with dozens of other delegates, alongside fellow Catalan CNT members Ángel Pestaña, Eusebi Carbó [ca] and Francisco Miranda Concha.
[10] Despite the controversy, he continued to contribute articles to Solidaridad Obrera, proclaiming his opposition to the possibility of Spanish intervention in World War I and publishing his thoughts on the upcoming 1918 congress of the CNT.
[11] When the congress of the CNT's Catalan regional federation was convened in Sants in June 1918,[12] Andreu's proposal for "single unions" was supported by Josep Negre and Salvador Seguí.