This particular pocket centered on the town and fortified submarine base of Saint-Nazaire but spread out further. North of the
Loire, the front line followed the left bank of the
Vilaine river, then the
Isac (the
Nantes-Brest canal), as far as the part of
Blain west of the canal; it then descended south-west to
Cordemais, passing between
Bouvron,
Fay-de-Bretagne and
Le Temple-de-Bretagne. South of the Loire, it included the municipalities of
Frossay,
Saint-Viaud,
Paimbœuf,
Arthon-en-Retz (La Sicaudais),
Saint-Père-en-Retz,
Saint-Brevin-les-Pins,
Saint-Michel-Chef-Chef,
La Plaine-sur-Mer,
Préfailles,
Sainte-Marie-sur-Mer and
Pornic. The coastal defensive sector of the pocket stretched over approximately of coastline. The Germans set up artillery batteries to defend the mouth of the Loire: • A battery of two 240mm calibre guns of French origin was sited to the north at
Batz-sur-Mer. • A similar battery was located south of the Loire on the
Pointe Saint-Gildas. • Between these two batteries were other more modest calibre guns, in particular at the with four 170 mm guns and four 105 mm guns, or, on the south shore, at Mindin and Pointeau in the commune of
Saint-Brevin-les-Pins. • There were also
anti-aircraft defences comprising 80 large calibre pieces divided into about twenty batteries. In total, the Germans had 700 guns of all kinds (fixed, mobile and anti-aircraft), with a higher density around the submarine base, the port facilities and the airfield. Closer to Saint-Nazaire, there was a belt of anti-tank ditches. The perimeter started from Fort de l'Ève, then north, crossing Marsac, Trignac, then along the
Grande Brière marshes, Montoir-de-Bretagne until reaching the estuary coast at
Donges. South of the Loire, the belt described a circle from
Paimboeuf to the south of Saint-Brevin. Altogether it is estimated that this pocket fortress had 28,000 German soldiers commanded by Aviation General . The submarine base remained under the command of Admiral . ==Allied forces around the pocket==