In August 1914 the Germans invaded Belgium giving their submarines direct access to the North Sea via Zeebrugge

the German constructed submarine pens at Bruges out of range of the guns of the Royal Navy's battleships

U-boats reached the English Channel via the Zeebrugge and Ostend canals

A German U-boat in the Ostend canal en route to the Channel

Zeebrugge harbour was heavily defended by German guns based on the Mole

Submarine nets were were laid across Zeebrugge harbour entrance

German submarines from Zeebrugge sank a huge number of cargo ships in an attempt to starve Britain out of the war