Maurice (Moss) Twomey (Irish: Muirgheas Ó Tuama; 10 June 1897 – October 1978) was an Irish republican and chief of staff of the Irish Republican Army (IRA).
Twomey was born in 1897 in Clondulane, near Fermoy, County Cork, Ireland and was educated by the Congregation of Christian Brothers. The son of a labourer at Hallinan’s Flour Mills in the town, Twomey went to work there at the age of 14 where he rose to the position of works manager. In 1914 he became active in the Irish Volunteers.
By 1918 he was adjutant of the Fermoy Battalion and a year later became an adjutant of the Cork No. 2 Brigade. He took part in an ambush of British troops in Fermoy in September 1919, one of the first attacks on British soldiers in Ireland since the 1916 Easter Rising and one of the first of the Irish War of Independence.
During 1920 he helped direct IRA intelligence in his brigade area. He was staff commandant of Liam Lynch’s 1st Southern Division when he was captured and imprisoned on Spike Island during 1921. He managed to escape from the prison by rowing boat along with Dick Barrett, Tom Crofts and Bill Quirke.
Twomey opposed the Anglo-Irish Treaty of December 1921, although he was critical of the tactics adopted by the anti-Treaty forces headquartered in the Four Courts - he was influenced by Oscar Traynor's opinion that garrison would destroy the Republic Éireann - Dublin during June 1922. Liam Lynch was a figure from the old IRA, dedicated to the cause, but also determined to fight. Four Courts showed the leadership that they were out of touch with the reality of the awesome power of artillery. Although reunited in adversity, the factional splits had not masked the changing nature political changes. Twomey concurred with Liam Mellows that if a government was to be formed in the interest of labour it must be a republic.