Early years

Known to his contemporaries as Sam, Mainwaring was born 15 December 1841 in Penrhiwtyn, Neath, Wales. He was a native speaker of Welsh and retained an affinity for the tongue throughout his life.^[1] Mainwaring was raised by his family as a Unitarian. He developed into a quiet yet persuasive public speaker and a tireless worker for activities which he believed important.^[1] In 1868, he married the daughter of a customs officer from Cardiff.^[2]

Mainwaring worked as an engineer, moving to the United States for a short period of time before returning to the United Kingdom to work in London, where he was a member of the Amalgamated Engineering Union.^[3]

Political career

Late in the 1870s, Mainwaring joined the East London Labour Emancipation League and was an early member of the Social Democratic Federation.^[3] However, this group proved to be a disappointment, failing to garner support of an appreciable section of the working class and was believed by many members to overly dominated by the intellectual pretensions and nationalist political views of its patriarch and patron, Henry Hyndman.

In 1885, there came a split in which Mainwaring joined with Eleanor Marx, Ernest Belfort Bax and his friend William Morris in forming the Socialist League.^[3] Over time, Mainwaring's views gradually evolved from revolutionary socialism to those of anarcho-communism.^[3]

In 1891, Mainwaring moved to Swansea and there started the Swansea Socialist Society.^[3] He became associated with the fledgling anarchist newspaper Liberty, edited by James Tochatti, formerly of the Hammersmith branch of the Socialist League.^[3]

In 1900, he played an active role in the movement opposing the Boer War.^[2]

In September 1903 and March 1904, Mainwaring published two issues of a short-lived newspaper called The General Strike, a publication which made detailed criticisms of the "officialism" of union bureaucracy and which publicised strikes in Europe making use of syndicalist tactics.^[4]

Death

In his later years, Mainwaring lived in London. On Sunday, 29 September 1907, while addressing a meeting on Parliament Hill Fields, Mainwaring was stricken by faintness and subsequently died.^[3] He was 65 years old at the time of his death.