He opened up a practice in Mitchelstown in County Cork. In 1874, he emigrated to the capital of Argentina, Buenos Aires. lieutenant is not known how Creaghe came in contact with anarchist ideas, since the country"s anarchist movement was small at the time, but he quickly became a follower of this idea.
In 1890, he moved to Sheffield, England, working in a poor working class district with many Irish immigrants.
On the group"s first public appearance, it sported a banner reading "Number God, Number Master" at the May Day demonstration. The group soon also founded a club and a newspaper, the Sheffield Anarchist, which did not survive for long as it became caught up in the Walsall Anarchists" trial.
In 1892, he left Sheffield to go back to Argentina via Liverpool, London, and Spain. There he founded the newspaper El Oprimido, forerunner of Louisiana Protesta, which exists to this day.
He was involved in the founding of the Argentine Regional Workers" Federation, an anarchist trade union.
He also contributed to the Ferrer free school movement inspired by the ideas of the Spanish anarchist pedagogue Francisco Ferrer. In 1911, Creaghe left Argentina once again, eventually arriving in Los Angeles, where he collaborated with Mexican anarchists. Both were involved in the Magonista rebellion of 1911 in Baja California.
After the start of the Mexican Revolution, they supported the country"s anarchist movement.
Creaghe died on February 19, 1920 in a prison in Washington, District of Columbia.
He became involved in the Socialist League, a Marxist group led by William Morris, but he soon broke away to form an anarchist group in Sheffield.