[1] In 1874, Spence was one of a number of militant mine-workers who formed the Amalgamated Miners' Association of Victoria, and he became the union's general secretary in 1882.

[3] Since the Australian economy was expanding rapidly at this time and there was an acute shortage of labour, the unions were in a strong bargaining position and were able to secure great improvements in the living standards of Australia's rural working class.

But a depression which began in 1891 led to acute class conflict as the mine owners and graziers tried to cut wages to remain solvent in the face of falling commodity prices, which the unions resisted.

There were bitter strikes in the maritime and pastoral industries, in which Spence played a leading role, although he was generally a force for moderation in the labour movement.

Spence supported the formation of the Progressive Political League, an early labour party, in Victoria in 1891 and he was narrowly beaten at a by-election in 1892 for the seat of Dundas in the Victorian Legislative Assembly.

Like most of the older generation of labour leaders who were born in the United Kingdom, Spence was associated with the more conservative wing of the Australian Labor Party, led by Billy Hughes.

At the 1917 federal election, although Hughes was easily returned to power, Spence lost his seat, mainly because the AWU organised the rural workers to oppose him.