The Zeebrugge Raid, which took place on April 23, 1918, was an attempt by the British Royal Navy to neutralize the key Belgian port of Bruges-Zeebrugge. The port was used by the German Navy as a base for their U-boats and light shipping, which was a serious threat to Allied shipping, especially in the English Channel. The raid was formally approved by the British Admiralty in February 1918 and launched two months later consisting of seventy five volunteer ships and two hundred soldiers. The raid began with a diversionary attack against the mile-long Zeebrugge mole. The attack was led by the old cruiser, HMS Vindictive, with two Mersey ferries, Daffodil and Iris II. The three ships were accompanied by two old submarines, which were filled with explosives to blow up the viaduct connecting the mole to the shore.