In 1932, the French army chose the ridges of the Sainte-Agnès mountain to erect a fort as a south bastion of the Maginot line. This line of fortifications was in service along France's borders with Belgium, Luxembourg, Germany, Switzerland, and Italy between 1928 and 1940. The fort of Sainte-Agnès consisted of underground blocks. It was flanked to the north by the fort of the Col des Banquettes, a small infantry barrier structure. To its south stood the fort of the Col de Garde, a small casemate that ensured the surveillance and the blocking of the road to Menton.