Arthur Le Moyne de La Borderie, (5 October 1827, Vitré, Ille-et-Vilaine – 17 February 1901, Vitré) was a Breton historian, regarded as a father of Brittany's historiography.
He came from La Borderie, which was an estate in the commune of Étrelles.
After studying law, he entered the École des Chartes. He left it in 1852 and from 1853 to 1859 worked in the archives of Loire-Inférieure. He was a founder member of the Société archéologique et historique d’Ille-et-Vilaine, of which he was president from 1863 to 1890.
Gaining recognition for his innumerable works on the history of Brittany, he enlivened research in many areas and inspired many historians by his influence and example. He was the director of the historic review Revue de Bretagne et Vendée (published from 1867 to 1900) that he founded aged 25.
He had been elected conseiller général of Ille-et-Vilaine from 1864 to 1871 then, the same year, député for Vitré, until 1876. In this role he was reporter of the Commission d’enquête sur les actes du gouvernement de la défense nationale (Commission of Inquiry into the Acts of the Government of National Defence). In particular he led the investigation into events at Camp Conlie where 50,000 Breton soldiers were held and supposedly mistreated in 1871. His report was overwhelmingly critical of the French army, which demonstrated a total lack of organization.
In the years after the Franco-Prussian War he re-formed the Association bretonne which had been dissolved as suspect by the government of Napoléon III. A large part of his library is now in the town library of Rennes, while the huge collection of original documents which he amassed is now housed in the departmental archives of Ille-et-Vilaine.