No idea who the guy is but the Sam Brown, long boots and FF (Fianna Fail) brass cap badge indicates he's an Irish Army Officer.
NCO'c (non commissioned officers) wear ankle boots and a belt without the shoulder strap.
The Irish Defense Forces personnell still wear the same badge on their caps and the same pattern is also on uniform buttons.
'Oglaig na hEireann'. In gaelic means 'The Irish Volunteers'
Oglaig > (soldier) volunteer.
'na hEireann' > of Ireland.
Kamila's information is spot on.
From
www.military.ie The Defence Forces' Badge
The Badge design (common to all Corps and services and all orders of dress) is derived from the badge of the Irish Volunteers.
The Badge originally adopted by the Irish Volunteers October 1914 as the official badge of the organisation. The Centrepiece is formed of the letters "FF". These letters signify "Fianna Fáil". The word "Fianna" is the name of the ancient military organisation (Circa 3rd Century A.D.) forming what then corresponded to the standing army of the country. The word "Fáil" means "Destiny". One of the ancient names of Ireland was "Innisfail" (The Isle of Destiny) and "Fianna Fáil" thus signifies the "Fianna (or Army) of Ireland".
The two letters are surrounded by a representation of an ancient warriors sword belt and a circle of flames which represent the "Sunburst" – the traditional battle symbol of the Fianna. The words "Óglaigh na hÉireann" inscribed around the sword belt mean "Soldiers of Ireland". No particular significance is attached to the representation of the star which was included to balance the design.
If you mail a copy of the photo to Irish Defence Forces Military Archives in Cathal Brugha Barracks. Rathmines Dublin 6, Telephone: + 353 (0) 1 8046457, I am sure that they will be able to assist very quickly in identifying the rank marking. Ranks and appointments were very confused in those days. Generals in the new army were often in their early 20s !!! Dashing out now but can supply further info later if required.
