Séré de Rivières system
Fort de Sucy was built following the Franco-Prussian War to defend Paris. Located to the southeast of Paris in Sucy-en-Brie, the fort was part of an outer ring of eighteen major fortifications built in response to improvements in the range and effectiveness of artillery since the construction of the Thiers fortifications of the 1840s. It was built in accordance with improved principles of fortification developed for the Séré de Rivières system.