On the morning of July 25, 1917, at No. 12 Colliery in New Waterford, Nova Scotia a devastating mine explosion erupted causing many casualties. It remains the worst mining disaster to have occurred on Cape Breton Island. There were 270 men and boys in the mine that day, 65 of whom lost their lives and many more were injured. Of the miners who were killed, 30 were from Cape Breton, 22 were from Newfoundland, and the rest were immigrants from Germany, Austria, Russia, and Italy.
The explosion occurred throughout the No. 5, No. 6, and No. 7 mine shafts, about 2000 feet below the surface. A coroner’s inquiry began just days after the incident. The Dominion Coal Company claimed that negligence was not a factor, and that the ventilation in the mine was in working order. This contradicted the accounts of many miners who testified that ventilation was poor and there was gas in the mine shafts. The coroner's jury found Dominion Coal Company "guilty of gross neglect" and recommended a thorough investigation into the cause of the explosion.
The provincial Department of Mines also conducted an inquiry, which included representatives from the miner's union, the Amalgamated Mine Workers of Nova Scotia (AMW). The Department's report recommended improvements to the mine's ventilation, but it did not blame the Dominion Coal Company for the explosion. The AMW demanded the Company be held to account. Their persistence led to the indictment of Dominion Coal Company for "causing grievous bodily harm" to their employees. Additionally, three officials within the company were charged with manslaughter: Angus MacDonald, a No. 12 Mine Manager; Alexander MacEachren, the District Superintendent of Mines; and Michael McIntosh, Deputy Mines Inspector. In October 1918, the case was brought before the Supreme Court in Sydney. The presiding judge was Humphrey Mellish, a former solicitor for Dominion Coal Company who had recently been appointed to the bench. After hearing witnesses for both sides, Mellish claimed there was insufficient evidence to convict the Dominion Coal Company and its three officials. He instructed the jury to issue a verdict of not guilty to all charges, which they did without deliberation.
J.B McLachlan was a union officer with the AMW and involved in the investigation. He and others from the union pressed the matter further, seeking justice and compensation for the miners' families affected by the disaster. McLachlan eventually won the appeal, and the victims' families were awarded additional compensation, but no one was held accountable for the mining disaster that claimed the lives of 65 men and boys.
In 1922, a monument was erected in New Waterford to commemorate the Number 12 Colliery mine disaster. Originally located on Ellsworth Avenue near the mine, the monument was later moved to Miners Memorial Park (now William Davis Square) just off Plummer Avenue, the town’s main street. It stands in honour and memory of those who lost their lives while mining coal and symbolizes the struggle for labour rights amongst coal miners in Cape Breton.