Question: Denis O'Brien was a veteran of what conflict that led to the establishment of the Irish Free State?
Sentence (from "Denis O'Brien (police officer)"): Detective Sergeant Denis O'Brien, Registration Number: 8288 (17 June 1899 – 9 September 1942), often called "Dinny O’Brien", was a veteran of the Irish War of Independence and the Irish Civil War.
Relevant evidence: Yes