Cremer established the International Arbitration League in 1870. He initiated an arbitration treaty between Great Britain and the USA. Cremer organized and promoted inter-parliamentary peace conferences, and he was editor of the journal "The Arbitrator". He was the only labor leader in the peace movement. Cremer was also one of the founders of the Inter-Parliamentary Union.
Member of the Council of the Inter-Parliamentary Union.
Gniewosz-Olexow wanted the Norwegian Nobel Committee to bestow an honorary peace award on Czar Nikolai II of Russia for his initiative that resulted in the 1899 Hague Peace Conference. In addition, Gniewosz-Olexow wished that the Nobel Committee would divide the prize money between some worthy peace workers, namely William Randall Cremer, Chevalier Descamps, Frédéric Passy and Bertha von Suttner.