Maclean was a supporter of Home Rule for Ireland but originally opposed an Independent Ireland because he was afraid that an Independent Catholic Ireland would be disastrous. He later became committed to Irish independence as part of a worldwide anti-imperialist struggle. He wrote a pamphlet called 'The Irish Tragedy: Scotland's Disgrace' which sold 20,000 copies. Following the Easter Rising he had contacts with members of the Scottish Divisional Board of the Irish Republican Brotherhood In the summer of 1907 he went on a speaking tour of Ireland, here he made friends with Jim Larkin. When the Easter Rising happened he distanced himself from it because he viewed it to be a Bourgeois-democratic revolution and in contradiction with his pacifist principles.