Abbé Louis Marie Olivier Duchesne (13 September 1843 - 21 April 1922) was a French priest, philologist, teacher and a critical historian of Christianity and Roman Catholic liturgy and institutions. Descended from a family of Breton sailors, he was born in 1843 in Saint-Servan, Roulais place, now part of Saint-Malo on the Breton coast, and was orphaned at a young age, in 1849, after the death of his father Jacques Duchesne. Marc Tanguy, a relative, was one of the survivors of 74-gun ship Redoutable at the Battle of Trafalgar in 1805. Louis' brother Jean-Baptiste Duchesne settled in Oregon, and arrived at Oregon City in 1849.