On May 1, 1890, demonstrations took place around the world at the behest of the Socialist International of left-wing parties.
The main demand was for limiting the working day to eight hours.
Frederick Engels noted that in all of continental Europe "it was Vienna that celebrated the holiday of the proletariat in the most brilliant and dignified manner."
But, he added, even this dramatic revival of the Austrian trade union and socialist movement was "thrown into the shade" by the "most important and magnificent" London May Day march and rally three days later.
What had, in Engels's words, roused the English workers from almost 40 years of slumber to join the great international army?
He pointed his German readers to the previous year's dockers' strike and the founding of the Gas Workers' and General Labourers' Union, which had grown to embrace 100,000 members.
He proclaimed the unionisation of huge numbers of unskilled workers and the fact that they wanted their unions to be led by socialists.
This rise of militant, left-led "new unionism" could be contrasted with the aloofness and conservatism, both industrial and political, of the craft-based unions led by the aristocrats of labour.