Keroman Submarine Base

Lorient, FR

The Keroman Submarine Base at Lorient was the largest and most capable U-boat facility ever constructed, consisting of three interconnected reinforced concrete bunkers — **Keroman I**, **Keroman II**, and **Keroman III** — built between 1941 and 1943 by Organisation Todt. The base served as home port to the **2nd**, **10th**, and **17th U-Boat Flotillas**, sheltering and servicing up to 30 submarines simultaneously. The bunkers' concrete roofs, up to **7.5 metres thick**, proved impervious to Allied bombing despite repeated raids by the RAF and USAAF; the structures are among the most enduring physical remains of the Atlantic Wall. By 1944, approximately **60% of all U-boat tonnage sunk in the Battle of the Atlantic** had been operated from Lorient. The city itself was almost completely destroyed by Allied bombing in January and February 1943 — 85% of structures levelled — yet the submarine bunkers survived intact. After liberation, the base continued in French naval service until the 1990s. Today **Keroman I** is open to visitors as a museum featuring the preserved submarine **Flore (Q160)**, while other sections remain within the **Marine Nationale** base.