the islands to France under the terms of Article 3 of the 1802 Treaty of Amiens; the last British forces left the islands in May 1802. Napoleon ordered the islands fortified and the work began in 1803. The primary defences consisted of a fort on Île du Large, 170 meters in diameter. The main structure is a circular fort with a diameter of 53 meters, with 48 firing ports for cannon on two levels of 24 casemates each. This work was completed by 1812. There are seven underground chambers and a cistern. The fort could accommodate 500 troops. In 1840 a lighthouse was constructed within the fort. German forces destroyed it during World War II. Later construction, between 1860 and 1867, added a quay, a powder magazine, and a semaphore station, the whole encircled with moats carved into the rock. The total complex covers 2.5 hectares. The quay has since disappeared, reclaimed by the ocean. In 1871, 200 Communards from the Paris Commune were incarcerated here in deplorable conditions. On Île de Terre, the fortifications date to between 1849 and 1858. They consist of a shore battery and a guard house capable of housing some 60 troops. Neither island was attacked again until the 20th Century. World War II In World War II the islands became the first French territory that seaborne Allied forces took on D-Day. At 04:30 on 6 June 1944 four US soldiers, armed only with knives, swam ashore from two-man canoes. When they had verified that the islands were unoccupied, 132 troops from 4th and 24th Squadrons of the U.S. 4th Cavalry Group landed on the islands to secure the approaches to Utah Beach. Although they faced no resistance, the US troops suffered 19 casualties, killed and wounded, from mines that the Germans had left. Nature reserve The French government directly administers the islands, which have the status of a protected nature reserve with restricted access. Île de Terre has been a designated nature preserve since 1967. Île du Large has been off-limits since 1991 for reasons of safety. The primary bird species are seagulls and cormorants. In winter tens of thousands of seagulls shelter on the islands. Although access to the islands is forbidden, anchoring between them is permissible. Currently, the fortifications are falling into ruins. Since 2003, the association "Les amis de l'île du large Saint-Marcouf" (Friends of Saint-Marcouf), together with students from the