She was born into the large family of Stephen O'Mara who was the Mayor of Limerick and an Irish nationalist.

Her family were nationalists and her father had resigned as a Member of Parliament in 1907 in order to support Sinn Féin.

[1] In 1910 she married James Mark Sullivan who was an Irish-born American coming back to Ireland to sort out family bequests.

[2] The business was registered in March 1916, by her husband,[2] they and Henry M.

[1] Knocknagow was not completed until the following year and is one of the two works of the company which are still extant.