Léchelle was born on 2 April 1760 at Puyréaux. As a young man he enlisted in the French Royal Army as a private and later became a fencing master at Saintes. When the French Revolution broke out he enrolled in the National Guard of Charente-Inférieure. In 1791 he became lieutenant colonel of the 1st "Charente" Battalion of volunteers. On 20 September 1792 the battalion fought at the Battle of Valmy as part of the Left Wing under Jean-Pierre François de Chazot. On 6 November that year the 1st "Charente" was at the Battle of Jemappes where it was included in François Richer Drouet's 1st Brigade of the First Line of the Left Wing under Jean Henri Becays Ferrand.