At Zeebrugge, there was a canal with wharves on either side of it and protected from the action of the sea by a long mole or breakwater. The plan was to fill three old cruisers, the Intrepid, the Iphigenia, and Thetis, with concrete, to attach mines to their hulls, work them into the very neck of the canal, and sink them across it. Two others similarly prepared were to be sunk in the harbor of Ostend. An old battleship, the Vindictive, aided by ferry boats, destroyers, smoke boats, motor launches, and indeed a whole swarm of craft, was to attack the great mole guarding the Zeebrugge Canal, create a diversion, and draw the fire of the German guns while the cruisers were working their way into the canal. To render the diversion convincing, blue-jackets and marines were to be landed on the mole and were to attempt to destroy such stores and guns as they could. The small motor launches were to carry off the crews of all these various vessels which were to be sunk and to render aid to any of the other craft which got into difficulties.

It was absolutely essential that all weather conditions should be exactly right. The night must be dark; the sea calm, so that the small craft might operate without too much danger; and above all, the Germans must be surprised. It was on the night of April 24, 1918, that the Vindictive, followed by two ferry boats, headed toward the mole, while around her rolled a thick smoke screen created by the small launches plying near by. The wind blew this toward the shore and concealed the ship, and it was not until she was close upon the mole that the wind suddenly changed, whirled away the smoke, and showed the startled Germans what was intended.

"There was a moment immediately afterwards," says the British official account, "when it seemed to those in the ships as if the dim coast and the hidden harbor exploded into light. A star shell soared aloft, then a score of star shells; the wavering beams of the searchlights swung around and settled to a glare. The wildfire of gun flashes leaped against the sky; strings of luminous green beads shot aloft, hung and sank." A tremendous fire from all the batteries upon the shore burst upon the Vindictive  as she laid her nose against the concrete side of the mole, thirty feet high. She let go an anchor and the two ferry boats, brought for the purpose, began to shove her up against the high side of the mole.

In order to get the sailors and marines on shore, it had been necessary to construct a series of drawbridges which could be lowered from the ship on to the mole, and up which the men must scramble, peppered all the while by German machine guns. The ship rose and fell with the tide more than had been expected. The gun fire was extremely severe and getting off the ship at all turned out to be an extremely hazardous and costly adventure. The men were magnificent, and as soon as possible swarmed on shore. The Germans abandoned the mole without a struggle and contented themselves with sweeping it with machine gun fire. One by one, the great store buildings and sheds burst into flames or crumpled as the dynamite which the British marines set went off.

Meanwhile the three cruisers were making their way into the canal. The first fouled one of the German defense nets and went ashore on a mud flat. The Intrepid, smoking like a volcano to conceal her from the Germans, and with all her guns blazing away at the shore, steered straight into the canal, followed by the Iphigenia. Her commander placed the nose of the ship on the mud of the western bank, ordered the crew into the motor launches clustering around, and blew up the ship by means of electric switches in the chart room. Four dull bumps told him that the work was complete. The Iphigenia  was then beached on the other side of the canal, blown up, and dropped exactly across the canal closing it from one side to the other. Her commander missed the motor launch, and was compelled to take refuge in a Corley float, a sort of life boat carrying a chemical which lighted a flare as it touched water. Originally intended to save the man by showing his position to the rescuers, it now picked him out as a target for the Germans and they promptly gave him unremitting attention. He was saved by drifting into a huge cloud of smoke thrown off by one of the cruisers, caught a rope from a passing motor launch, and was towed along for a while before he could be hauled on board.

As his launch cleared the canal and came forth into the open harbor, the water spouting all about them from the German shells, they saw the success of another phase of the expedition. An old submarine laden with explosives had been run into the mole, her crew picked off by the waiting motor launches, and blown up. "A huge roaring spout of flame tore the jetty in half and left a gap of over a hundred feet." It would be some time before the Germans would get out again upon the mole. The Vindictive, her work done, now blew her whistle, gathered in such of her men and wounded as she could, was pushed off from the mole by the two ferry boats, and limped out of the harbor, literally riddled with shot and shell. There she was received by destroyers and cruisers who were supporting the operation.

An attempt made that same night on the harbor of Ostend was a failure, but on May 11, the Vindictive  herself successfully carried out the enterprise. The night promised well; it was nearly windless, the sky a leaden blue and with no moon; the sea was still, enabling the motor craft to cooperate. In the darkness, without a light, the Vindictive  made her way towards the shore, shrouded with smoke thrown up from the smoke ships. A motor boat preceding her lighted flares on the water to show the way to the harbor mouth. Fifteen minutes before the ship was due at the entrance, two motor boats dashed in and torpedoed the high wooden piers on either side of the entrance, both vanishing in the roar and leap of flame and debris.

Suddenly there appeared high in the air a flame that sank slowly earthwards, a signal from the fleet of aëroplanes, cruising over the town, ready to drop bombs upon it at the proper moment. The same instant came the shriek of the first shells thrown from the great guns of the British marine artillery, brought up to occupy the German heavy artillery. A tremendous roar from the shore replied as every one of the many guns began action. Star shells shot up, lighting the great smoke plumes; green flares and strings of luminous green balls, which the airmen called "flaming onions," soared up and lost themselves in the clouds. Through all the glare and hail of shell, the Vindictive  pushed steadily on.

And then came a fog, a real fog, dense, thick, moist! The Vindictive  lost her way; the motor boats could not see each other; their flames were lost in the fog. Twice the old battleship cruised across the harbor entrance, missing it both times. The third time there came a sudden rift in the mist and she saw the entrance dead ahead. She steamed over the bar and once she was in the German guns poured shells upon her. She was hit every few seconds, her decks and turrets destroyed, her guns put out of action, her officers and men killed and wounded. She laid her battered nose against the eastern pier and tried to swing across the channel, but she was too hard and fast in the mud to be moved. They blew the main charges beneath her, tearing out her bottom plates and sinking her in the channel. Her commander was dead already and many of the officers. Every man alive was taken off in motor launches which immediately ranged alongside. One by one, they made their way through the fog, back to the waiting cruisers and destroyers outside. The deed was done. Ostend harbor would no longer be useful to the Germans.