In 1891 Henry Salt joined up with a small group of like-minded folk to draw up a manifesto and launch the Humanitarian League. The idea was to proclaim a general principle of humanness underlying the efforts of those societies (SPCA (now Royal), vegetarian and anti-vivisection societies, anti-war groups, Howard Association for Penal Reform, etc) which aimed at humanising public opinion; and the consequence being that it would show that while the various efforts were disconnected, they were inspired by a single bond of fellowship and universal sympathy.
In its manifesto it was asserted “that much good will be done by the mere placing on record of a systematic and consistent protest against the numerous barbarisms of civilisation — the cruelties inflicted by men, in the name of law, authority, and traditional habit, and the still more atrocious treatment of the lower animals, for the purpose of ‘sport’, ‘science’, ‘fashion’, and the gratification of an appetite for unnatural food”.
Salt was General Secretary, Editor and founder of the Humanitarian League and the League's Journal from 1891 to 1919. He received considerable support from friends and supporters until it closed. The League was opposed to all avoidable suffering on any sentient being. Salt worked with the RSPCA and other organisations, and made systematic and consistent protests against numerous "barbarisms". His 'battles' in the Lords and House of Commons are recorded in the League's journal.
Salt edited two journals for the Humanitarian League, Humanity, later renamed The Humanitarian (1895-1919), and The Humane Review (1900-1910). He also appointed special departments to deal with cruel sports, criminal law and prison reform, humane diet, education of children and opposition to war.
Not all of his support came from the ‘Left’. The Hon. Fitzroy Stewart, Secretary, Conservative Office, supported him on the question of stag-hunting, and is but one of many examples.
Salt also enlisted many able people to carry out reform of criminal law and prison reform. Dr W. Douglas Morrison, a criminologist, led the League's agitation which helped bring about the Prison's Act of 1898, and W.S. Monck (Lex) worked for the establishment of a Court of Criminal Appeal and the revision of imprisonment for Debt Law.
The Humanitarian League wound itself up in September 1919 after a vote at a special general meeting of 150 to 15 (Humanitarian, vol. VIII, no. 195, September 1919, p.165).