Grosmagny is administratively attached to the Township Giromagny. The village is situated on the sunny side of the Vosges Mountains on the edge of the forest, at altitudes between 430 and 600 meters. The road that crosses the route follows a Roman road linking Langres in Strasbourg following the foot of the Vosges.
The first known citation Aggrum Masnil dates from the mid 12th century.
When sharing the estate of Joan Montbéliard, daughter of Renaud de Bourgogne, the stronghold of Grosmagny fell to Jeannette Ferrette, his daughter, who married the Archduke Albert of Austria second.
The village depended on the parish of Rougegoutte until about 1796, when construction of the Saint-Georges. It was built at that time in independent parish and the village it was annexed by Eloi.
On November 2, 1870 took place in heavy fighting between the Prussians and mobile Haute-Saone. Father Miclo, Étueffont vicar, who went to the wounded, was shot by an enemy officer. A monument, located along the old road Petitmagny illustrates this tragic episode.
