The outbreak of boats with metal hulls instead of wood forced the Ministry of War to update coastal defenses. A decision of July 1846 fit the coasts with forts and reduits. Around 1853, the redoubt of Tatihou faced a type-1846 reduit on an islet. Some 60 men took care of 12 cannon ports in a 236 by 171 ft (72 by 52 m) enclosure. Today, the islet is home to the ornithological reserve of Tatihou. It is forbidden to visitors and remains a place of freedom for a varied birdlife of more than 150 species.