John O'Brien (jack) was my husband's great grandfather too. I was just talking about him this evening with my father in law, Paddy O'Brien, he is the grandson of John (jack). His dad Pat was just a few weeks old when his father was killed in 1920. The funeral was in St Patrick's chapel in Donegall Street. He left behind his widow Sarah and children Sarah, Margaret, John and a few more. Names available in census.ie