The Flanders flotilla was constituted in March 1915 at the port of Bruges in occupied Belgium. Commanded by Kapitänleutnant Bartenbach, the force comprised nine UB- and seven UC- type U-boats, small mass-produced coastal types suited for operations in the closed waters of the Channel and the North Sea.[1] UB boats were prefabricated in Germany and brought in sections to Bruges and assembled.