Vice-Admiral Roger Keyes (later Baron Keyes of Zeebrugge and Dover) had taken command of the Dover Patrol on 31 December 1917. He was charged with the task of stopping the marauding submarines and destroyers working out of occupied Belgium. The threat came from the main German naval base at Bruges, an historic inland town linked to the sea by two canals, one to Ostend and one (usable by the largest vessels) to Zeebrugge. Keyes’ plan was to close the canal entrances at the two ports with blockships. To increase the chances of success at Zeebrugge, there was to be a landing on the fortified mole to put its guns out of action and cause as much damage as possible.
The submarine C3 ran a gauntlet of fire to demolish an iron viaduct forming part of the mole. Beneath it she was blown up to prevent German reinforcements reaching the end of the mole. Some 15 minutes into the assault the ‘Thetis’ passed the end of the mole, repeatedly hit and with her own gunners blinded by smoke she failed to make the lock gates. The ‘Intrepid’ following her was sunk on the western bank of the canal entrance, while the ‘Iphigenia’ was grounded to still further close the gap.At 1:10 am the sirens sounded for withdrawal and in 20 minutes the embarkation of the survivors was completed. The Iris was hit twelve times as she made her departure with heavy loss of life among the men packed on board. Battered almost beyond recognition, the ‘Vindictive’ limped back to Dover. The cost of the action was 214 men killed and 383 wounded. The heroic achievement of the men involved in the attack can be seen in the decorations awarded for the action on St George’s Day. Over 200 decorations were earned that night including eight Victoria Crosses, which worked out at a rate of six medals for every minute of the action.The attack on Ostend was unsuccessful, as the blockships had run aground before reaching the canal entrance. On 9 May, in a second raid, ‘Vindictive’ returned to the Belgian coast. She had been patched up and partly filled with concrete, and in the face of heavy fire was sunk in the canal entrance at Ostend.
The cruiser ‘Vindictive’ was made ready to lead the assault on the Zeebrugge mole. Inessentials were stripped, her armament was augmented by howitzers, flame throwers and mortars, while ramps for landing troops were hinged to her port side. With her would go the Mersey ferry boats Iris and Daffodil commandeered by the navy, and fitted out with mattresses and steel plating to give troops some protection on their upper decks. The old 3,600-ton cruisers ‘Thetis’, ‘Intrepid’ and ‘Iphigenia’ were converted into block ships, filled with 1,500 tons of concrete and fitted with electrically fired scuttling charges. 700 Royal Marines and 200 Royal Navy seamen were trained for the assault. More than 160 ships were involved and assembled at Dover and in the Thames Estuary. Twice the ships sailed and were forced to turn back due to the weather. They left finally on 22 April, the eve of St George’s Day, when from the destroyer ‘Warwick’ Keyes made his famous “St George for England” signal. From the ‘Vindictive’ came the reply “May we give the dragon’s tail a damn good twist”.The Ostend force parted company 40 minutes before the main force reached Zeebrugge. As the ‘Vindictive’ emerged from the fog and smoke screen the German batteries on the mole opened up on her. Even before being pushed up against the mole at one minute after midnight by the ‘Daffodil’, the ‘Vindictive’ had been seriously hit. In the rain of shells landing parties on her decks were decimated striving to cross the gap from the rolling ship. A howitzer crew was killed or wounded and the replacement crew wiped out.
After the war the people of Zeebrugge presented Dover with the Zeebrugge Bell, which had hung on the end of the mole and was rung by the Germans to warn of a British attack. The bell is housed on the front of the Old Town Hall, where it is rung every year on St George’s Day in honour of the Dover Patrol.