B 103 is a former military bunker or fortified position located in the countryside near Saint-Pol-de-Léon in the Finistère department of Brittany, France. Its designation, "B 103," strongly suggests it was part of a numbered battery or strongpoint system, most likely from the Second World War. The region of Brittany, and specifically the northern coast near the Roscoff harbor, was heavily fortified by German forces as part of the Atlantic Wall coastal defense network. While the specific unit that occupied this position is not recorded in the available data, such positions typically housed artillery pieces, observation posts, or ammunition stores to defend against Allied naval and amphibious assault.
The strategic importance of this location derives from its proximity to the English Channel and the significant port of Roscoff. Controlling this stretch of the Breton coast was crucial for German naval operations and to protect the approaches to the larger U-boat bases on the French Atlantic coast. The bunker's construction would have involved reinforced concrete (often referred to as beton) and standard German Widerstandsnest (resistance nest) or Stützpunkt (strongpoint) designs, intended to be mutually supporting with other nearby fortifications.
Following the war, many of these isolated coastal and inland bunkers were stripped of useful equipment and abandoned. B 103 now stands as a relic of the extensive militarization of the French coastline during the German occupation. Its current condition is likely that of a concrete ruin, overgrown and partially buried, serving as a silent testament to the conflict. The exact nature of its armament or the