The National Union of Mineworkers (NUM) is a trade union for coal miners in Great Britain, formed in 1945 from the Miners' Federation of Great Britain (MFGB). The NUM took part in three national miners' strikes, in 1972, 1974 and 1984–85. After the 1984–85 strike and the subsequent closure of most of Britain's coal mines, it became a much smaller union.