Miège was born in a house called La Forêt, in the village of Mercury (close to Albertville), in the Duchy of Savoy[1][2] as the youngest son of a wealthy and pious family.

[5] He later taught moral theology at the Jesuit house of probation in Florissant, and became prefect of discipline and professor at Saint Louis University in 1851.

[4] On July 23, 1850, Miège was appointed the first Vicar Apostolic for the Indian Territory east of the Rocky Mountains, as well as Titular Bishop of Messene, by Pope Pius IX.

[5] At that time, his vicariate (which comprised the greater part of what is now Colorado, the Dakotas, Kansas, Montana, Nebraska, and Wyoming) contained five churches, eight priests, and 5,000 Catholics.

[4] In August 1855, he established his episcopal see at the prosperous city of Leavenworth in order to better minister to the growing number of white settlers there.

[3] As the number of churches and schools increased, Nebraska was formed into a separate vicariate in 1857 and the Kansas Territory was left under Miège's jurisdiction.

[1] In 1871, desiring a return to the private ranks of the Jesuits, Miège sent his petition to be relieved of his office to the Holy See, which instead gave him Louis Mary Fink, O.S.B., as a coadjutor.