Edward Conor Marshall O’Brien, Irish aristocrat and intellectual, is born in Cahirmoyle, County Limerick, on November 3, 1880. His views are republican and nationalist. He is also owner and captain of one of the first boats to sail under the tri-colour of the Irish Free State. He is the first amateur Irish sailor to sail around the world.

O’Brien is a ship builder and designer, and his notable boats include the Kelpie (used for gun running in 1914), the Saoirse (in which he circumnavigates the globe) and the Ilen (a Falkland Islands service ship).

O’Brien’s grandfather is William O’Brien who is a member of Young Ireland. His grandfather and his aunt Charlotte Grace O’Brien both play roles in social reform. Robert Donough, his uncle, is an architect, and the painter Dermod O’Brien is his brother. He is educated in England at Winchester College and the University of Oxford, and in Ireland at Trinity College Dublin (TCD). After his education he comes back to Ireland and starts practicing as an architect in 1903. According to the 1911 census he lives at 58 Mount Street, south County Dublin.

O’Brien is credited with two buildings in his lifetime: the Co-operative Hall in County Donegal and the People’s Hall in County Limerick. He is also known as a naval architect, having designed two ships, the Saoirse and the llen. He later captains both of these ships himself.

In Saoirse, a 20-ton, 42-foot ketch designed and built in 1922 in Baltimore, County Cork, he and three crew members circumnavigate the globe between 1923 and 1925 – the first recorded by an amateur skipper from west to east, the first yacht circumnavigation by way of the three great capes: Cape Horn, Cape of Good Hope and Cape Leeuwin, and the first boat flying the Irish tri-colour to enter many of the world’s ports and harbours. His voyage begins and ends at the Port of Foynes, County Limerick, where he lives. His account of the voyage, Across Three Oceans, (1927) becomes one of the classics of maritime literature.

Up until O’Brien’s circumnavigation, this route is the preserve of square-rigged grain ships taking part in the grain race from Australia to England via Cape Horn (also known as the clipper route).

O’Brien’s seagoing experiences are put to use in his design of the Ilen, which is built for the Falkland Islands as a service boat and launched in the spring of 1926. In 1998, Ilen returns to the site where she was first built, on the River Ilen near Baltimore, County Cork, where she undergoes a full restoration and is re-launched in May 2018. This task provides work-based learning for the students of the Ilen School.

O’Brien has some involvement with gun running in 1914 on behalf of the Irish Volunteers, for political reasons and because he has experience in sailing. On July 26, 1914, nine hundred guns are brought to Howth harbour aboard Erskine Childers‘ yacht Asgard. As part of the same operation, O’Brien transports arms on his yacht, Kelpie. The guns on Kelpie are transshipped to another yacht, Chotah, owned by Sir Thomas Myles, before being landed at Kilcoole in County Wicklow on August 1, 1914. After the gun running incidents, he serves in the Royal Naval Volunteer Reserve.

O’Brien is a keen mountaineer as well as a sailor, known for climbing in bare feet. He climbs Mount Brandon in southwest Ireland and Snowdon in North Wales with George Mallory and Geoffrey Winthrop Young among others. Later, during his circumnavigation (1923–1925) he plans to climb Aoraki / Mount Cook in the Southern Alps in New Zealand‘s South Island. However, because of delays during his circumnavigation, he arrives in New Zealand too late.

In 1928, O’Brien marries a well-known artist, Kathleen Francis, the youngest daughter of Sir George Clausen, RA. The couple thereafter moves to Ibiza, where they live on the Saoirse until Kathleen’s death in 1936. They have no children. Relocating to Cornwall, where he lives with his sister, he writes books on sailing and works of fiction for children. Although too old for active service when war with Germany breaks out in 1939, he assists the British war effort by serving in the Small Ships Pool, which delivers support vessels across the Atlantic and brings food supplies from the United States in private yachts.

In 1940 O’Brien sells Saoirse to the Royal Cornwall Yacht Club. The boat remains in use until 1980, when it is lost off the Jamaican coast. After the war he retires to another sister’s home in Foynes, County Limerick, where he lives and continues to write books for children until his death on April 18, 1952.