Having taken his MA in History at UCD, Gallagher joined the Civil Service applying for a position in the Department of External Affairs, as it was then called, starting in the job on 6 January 1969. His first minister was Frank Aiken, who usually talked to him in Irish, having learned that his new junior official was fluent in the language. Later that year, Aiken was succeeded by Dr Patrick Hillery and then the event took place that was to shape Gallagher's life: the North erupted into violence.