 Lamy's ambition to become an officer developed very early; at ten-years-old, he entered the Prytanée National Militaire, where he won the first prize in Geography in the general concourse of all the department's school, a possible sign of his future colonial career.In 1877 he entered at Saint-Cyr, the foremost French military academy.Lamy began his career in 1879 as a Second Lieutenant in the First regiment of Algerian tirailleurs.