[2] During the last days of World War II, his family was informed that one of MacKernans' uncles had died, one of three who were serving in the Royal Air Force, an event he was to frequently recall in his subsequent career.
He then attended the Sorbonne and the Bibliothèque nationale de France,[5] while also teaching at the Lycée Condorcet, earning a master's degree focussing on the works of Jean-Paul Sartre and becoming fully bilingual in French and English – he was already an Irish speaker.
[4] In 1964, he joined the Irish Department of Foreign Affairs[2] and in 1965 was assigned to the United States, initially to Boston as vice-counsel and later New York as deputy counsel general.
[2] In 1969, he assisted with the development of Ireland's case in relation to the Northern Ireland conflict for the United Nations Security Council, embarking on trips with then Minister for Foreign Affairs (later President) Patrick Hillery to Ottawa in Canada and Washington, D.C. in the United States in search of support from politicians and people there.
[3][18] His achievements in France were recognised by the French Government when he was honoured as a Grand Officier de l'Ordre national du Mérite shortly before his retirement.
[19] In January 2010, he died of idiopathic pulmonary fibrosis,[2] survived by his wife Caitríona and sons Dónal, Colm and Dara.
[2] Labour Party TD Ruairi Quinn paid a special tribute,[1] followed later by Enda Kenny, the leader of the opposition and Fine Gael, the Tánaiste (deputy prime minister) and other political figures in the houses of the Oireachtas.