Breen was married on 12 June 1921, during the War of Independence, to Brigid Malone, a Dublin Cumann na mBan woman.
They had met in Dublin when she helped to nurse him while he was recovering from a bullet wound.

Seán Hogan was best man, and the bride's sister Aine Malone was the bridesmaid.
Photographs of the wedding celebrations taken by 5th Battalion intelligence officer Séan Sharkey are published in The Tipperary Third Brigade a photographic record.
Breen was at the time one of the most wanted men in Ireland, and South Tipperary was under martial law, yet a large celebration was held.
The wedding took place at Purcell's, "Glenagat House", New Inn, County Tipperary.
Many of the key members of the Third Tipperary Brigade attended, including flying column leaders Dinny Lacey and Hogan.

The Breens had two children, Donal and Granya.

Breen was an atheist.
Breen was married on 12 June 1921, during the War of Independence, to Brigid Malone, a Dublin Cumann na mBan woman. They had met in Dublin when she helped to nurse him while he was recovering from a bullet wound.
Seán Hogan was best man, and the bride's sister Aine Malone was the bridesmaid. Photographs of the wedding celebrations taken by 5th Battalion intelligence officer Séan Sharkey are published in The Tipperary Third Brigade a photographic record. Breen was at the time one of the most wanted men in Ireland, and South Tipperary was under martial law, yet a large celebration was held. The wedding took place at Purcell's, "Glenagat House", New Inn, County Tipperary. Many of the key members of the Third Tipperary Brigade attended, including flying column leaders Dinny Lacey and Hogan.
The Breens had two children, Donal and Granya.
Breen was an atheist.
Dan Breen