[4] In 1869, Mottershead was elected to the General Council of the International Workingmen's Association, on which he was long known as an ally of Karl Marx, and acted as its corresponding secretary for Denmark.
However, he fell out with Marx, in particular due to his refusal to consider Irish independence, and lost influence in the association after attending the 1872 Hague Congress while drunk.
A meeting of 5,000 workers at Preston Corn Exchange, chaired by Alfred Bailey, resolved to support his candidature.
[9] When a by-election arose later in the year, Mottershead was again proposed as a candidate, although ultimately the election was unopposed.
[9] In the late 1870s, Mottershead was a member of the executive of the Labour Representation League, using this position to campaign against war with Russia.