The warship HMS "Vindictive" and two River Mersey passenger ferries, the "Royal Iris" and the "Royal Daffodil" were used to carry in the landing parties and all three vessels were given extra protection to their superstructure to help shield them from the German guns which were expected to be firing at them from almost point blank range.

More than 70 vessels, including submarines, rescue launches and smoke-laying motor boats, took part in Operation ZO along with more than 1,700 men. At first a huge smokescreen laid by the fast motor boats hid the British fleet from the guns on the mole, but at a vital moment the wind changed and the smoke cleared. The "Vindictive", which was less than 100 yards away from the pier, came under immediate heavy fire and was hit. Several key officers and a number of men were killed and 32-year old Lt Cdr Harrison was knocked unconscious with a broken jaw.

When he regained consciousness he found himself in charge of the raiding parties. Despite his injuries, he gathered together a handful of men and led a charge along the mole parapet in the face of heavy machine gun fire. He was killed at the head of his men, all but two of whom were also killed. One of those wounded was a Londoner, Able Seaman Albert McKenzie, who used his Lewis gun to fight his way to the end of the fortified mole until the weapon was blown out of his hands by a German round. McKenzie then continued to fight with his revolver until he was forced to retreat back on board the "Vindictive" after being shot in the back and right foot. He recovered from his wounds, but seven months later died from influenza.

[ London Gazette, 17 March 1919 ], Zeebrugge, Belgium, 22 and 23 April 1918, Lieutenant Commander Arthur Harrison, Royal Navy

For most conspicuous gallantry at Zeebrugge on the night of the 22nd - 23rd April 1918. This officer was in immediate command of the Naval Storming Parties embarked on "Vindictive".

Immediately before coming alongside the Mole, Lieut-Commander Harrison was struck on the head by a fragment of a shell which broke his jaw and knocked him senseless. Recovering consciousness he proceeded on to the Mole and took over command of his party who were attacking the seaward end of the Mole. The silencing of the guns on the Mole head was of the first importance, and though in a position fully exposed to the enemy's machine-gun fire Lieut-Command Harrison gathered his men together and led them to the attack. He was killed at the head of his men, all of whom were either killed or wounded.

Lieut-Commander Harrison, though already serverely wounded and undoubtedly in great pain, displayed indomitable resolution and courage of the highest order in pressing his attack, knowing as he did that any delay in silencing the guns might jeopardise the main object of the expedition, i.e., the blocking of the Zeebrugge-Bruges Canal.