The Miners' Federation was formed as a national union when representatives of regional miners groups from the coalfields of New South Wales, Queensland, Victoria and Tasmania united in Sydney in 1915.

Fourteen years later, the Miners' Federation faced its sternest test when 10,000 men and boys were locked-out of their pits for 15 months (1929-1930) in the Unions largest region, the Northern District of NSW. At that time the Miners’ Federation was led nationally by General President Dan Rees and General Secretary Dai Davies with "Bondy" Hoare as the Northern District President.