The biographical information includes his birth on 31 July 1877 in Paris's 10th arrondissement to Pierre Volant and Salome Schuch. He was a restaurant waiter residing at 31 Rue Milton in the 9th Paris arrondissement at the time of his military registration, and was assigned number 782 in the conscript class of 1897. He was described as 1.66 meters tall, with blonde hair and blue eyes, and a strong chin.
Louis Volant presented himself for service with the 150e Infantry Regiment on 18 November 1898. During his two years of active Army service, Louis Volant was promoted to Corporal in July 1899. On 30 December 1899 he was granted leave prior to his transfer into the Reserve Army, which was officially completed on 1 November 1901. His two required exercise periods during his stint in the active army reserve were waived due to the fact that he was residing in England.
In late 1911 Louis Volant's required military service was transferred to the French Territorial Army, where he remained until the entire French Army, including territorial reserve forces, was mobilized via Presidential decree on 1 August 1914. Louis Volant rejoined with the 16th Territorial Infantry Regiment on 4 August 1914, the day after Germany declared war on France.
With the 16th Territorial Infantry Regiment, Louis Volant was guarding the village of Courcelles-le-Compte in October of 1914 when it came under attack from German forces attempting to battle their way through to Paris, a series of battles that were later termed The Race to the Sea. He was gravely injured by an explosive shell on 9 October 1914, with wounds to the left side of his back, as well as his right arm, which was injured so badly the bone was exposed. Corporal Volant was cited for his bravery in this battle by order of the 88th Regiment on 29 August 1915 for showing remarkable qualities of cold-blooded calm and energetic activity during the battle, as he took command of a section and maintained his men's defense under heavy fire during retreat. He is also noted as having killed several German soldiers with complete calm and composure.
Louis Volant returned to active service and remained in armed combat until 30 December 1918. His residences throughout his service correspond with the addresses where Louis Volant, great-grandfather of J.K. Rowling, were known to be living. This includes 95 Mortimer Street, Cavendish Square, London in November 1899; 35 Seymour Place in London in January 1900 (just following his marriage to Eliza Mary Ann Smith); and Rue Albert Street in London in December 1918 where he returned to the family following his WWI service in France.