John Brennan was born 17 May 1876, son of Martin & Catherine (née Canavan) Brennan at the village of Develeash which in Irish is An Dubh Lois, meaning ‘The Black Fort’. . The family farm (shown above) is a short distance from Kiltimagh, Co. Mayo, Ireland.
John Brennan married Margaret Moran (daughter of Patrick Moran & Catherine Stanton). They subsequently had nine children: