The Aberdare strike of 1857-8 was one of the first significant industrial disputes in the history of the steam coal trade of South Wales. The origins of the strike lay in the decision of the employers to impose a wage reduction of up to 20%, as a result of the general depression in trade in the aftermath of the Crimean War. During the dispute a trade union appeared amongst the miners of the Aberdare Valley but the men were ultimately forced to return to work on the terms set by the owners.
During the autumn of 1857 it was widely rumoured that the coal owners were intending to impose a substantial reduction in wages. Amongst the miners there was a general recognition that some reduction was inevitable and a delegate meeting agreed to send a delegation to local coal owners to argue for a limited reduction. This conciliatory approach was supported by some influential local middle-class figures, most notably Thomas Price, influential minister of Calfaria, Aberdare and also editor of the Welsh language newspaper, Y Gwron (which was published at Aberdare). However, when the masters refused to negotiate, the miners rejected the conciliatory advice of Price and came out on strike.
In the early phase of the strike, there were rumours of some violence and intimidation, largely towards those engineers who were maintaining the pits in working order. It appears that the engineers succeeded in doing so at all pits, apart from that at the Shepherds Pit, Cwmaman, where the engineers themselves joined the dispute. In this tense atmosphere, soldiers were sent to Aberdare. Having initially been lodged at the Town Hall, the redcoats were removed to Cardiff when fears of disorder subsided. This appears to have resulted from the intervention of the local Member of Parliament, Henry Austen Bruce. In general, however, the dispute was a peaceful one and was characterised by the emergence of a trade union movement, and the Merthyr Telegraph, in particular, was critical of other newspapers in Cardiff and Swanase which it accused of wildly exaggerating the extent of disorder at Aberdare.
The coal owners of the district, in contrast to the iron masters, were, in the main, self-made Welsh entrepreneurs whose relationship with their workmen were generally good. Men such as David Williams (Alaw Goch) now found themselves in the unfamiliar position of being opposed by their employees. In a letter to the Merthyr Telegraph, Williams rejected the claims made by the miners that there was no reduction in the price of steam coal. He did not blame the men for seeking to sustain their wages but did allude to the threats being made, including flooding the mines.