On 27 July 1938, Lefèbvre was appointed bishop of Troyes by Pope Pius XI. He received his episcopal consecration on 11 October from Bishop Edouard-Gabriel Mesguen, with Bishops Joseph-Jean Heintz and Louis Liagre as co-consecrators.
On July 27, 1938, Lefèbvre was appointed bishop of Troyes by Pope Pius XI. He received his episcopal consecration on October 11 from Bishop Edouard-Gabriel Mesguen, with Bishops Joseph-Jean Heintz and Louis Liagre serving as co-consecrators.