Smillie became secretary of the Larkhall Miners' Association in 1885 after presiding over a mass meeting, which ended in its formation and when the county federation was formed, he became president in 1893. He became the President of the Scottish Miners' Federation in 1894. Employers in a number of districts demanded wage reductions, resulting in strikes. Following a special conference of the Miners Federation of Great Britain, a ballot was taken, and the strike that followed lasted from June until October 1894. Controversy arose between Smillie and Chisholm Robertson in 1900 led to a debate at Glasgow Trades Council, which Smillie won. Strikes left the Scottish miners in a greatly-weakened position, who suffered further wage cuts in 1895 and 1896. In 1897, less than 20% of the workers were organised.