The ouvrage is located at an altitude of 663 metres (2,175 ft) on the Agaisen massif overlooking Sospel from the north.

[2] Ouvrage l'Agaisen was built between November 1930 and December 1934, beginning with a contractor named Marting and completed by Roussel.

The heavy machine gun cloche in Block 2 fired on Italian forces in the area of the advanced post at Castes-Ruines.

[9] Some of the fort's armament was removed under the terms of the 25 June 1940 armistice, but the ouvrage was maintained by French forces through the war, albeit in a militarily decommissioned capacity.

l"Agaisen was occupied by German forces after their withdrawal from the war in 1943, remaining until the allied invasion of Southern France in 1944.

During fighting around Authion in April 1945 the 75mm turrets of l'Agaisen and Monte Grosso were used in support of American and French forces in the area.