It was the organ of the radical socialist Free Association of German Trade Unions (FVdG).
The FVdG's founding congress in Halle in 1897 decided to publish a newspaper fortnightly under the name Solidarität (Solidarity).
Organ der lokalorganisierten und durch Vertrauensmänner zentralisierten Gewerkschaften Deutschlands, which was changed to Einigkeit.
Organ der Freien Vereinigung deutscher Gewerkschaften in 1901, the year the federation was renamed to Free Association of German Trade Unions.
During World War I, both Die Einigkeit and Der Pionier were banned by the German authorities.