As would happen in the Second World War, the Allies in the First World War had a great deal of trouble dealing with German U-Boats. At the beginning of the war there were stringent rules against unrestricted submarine warfare on civilian/merchant ships. The rules stated that a submarine would have to stop, board, and inspect merchant ships. If there was contraband on board they would have to evacuate the ship before firing upon it. However this was impractical since the crew of the submarine were responsible for the ship's crew, so many did not even bother with non military ships...that is until 1915. When the British placed a blockage along the North Sea to prevent war materials from being imported via the sea to Germany, the Kaiser and his war cabinet authorized unrestricted submarine warfare in retaliation to British shipping. And initially it proved to be very effective. That is until the passenger liner Lusitania was sunk off the coast of Ireland that year. Over 1,200 civilian casualties, including over 120 Americans caused such a worry that the United States would declare war that the Germans suspended the war on merchant shipping.
However, by 1917 the stalemate in the west and the effect of ever increasing shortages at home and on the front due to the blockade caused the Germans to create a plan to win the war while the German war machine was strong. It included many things such as knocking Russia and Italy out of the war as well as the resumption of unrestricted submarine warfare on British shipping. Knowing it would cause the U.S.A. to likely enter the war, the goal was to knock the British out of the war before Yankee troops arrived by depriving England of supplies and shifting men and material away from Italy and Russia to the west.
German U-Boats were in no time causing such severe damage to the British shipping that it looked grim for the United Kingdom. The British were losing ships much faster than they could be replaced and the lack of material was causing problems at home. Strict rationing was implemented and even then shortages began to show up at the front. Great Britain had not been able to feed itself in over a hundred years and the possibility of being starved out of the war was a danger unless the U-Boat threat was contained. In order to do this several actions were implemented. First, the British laid an extensive mine field between Scotland and Norway to prevent subs from getting access to the Atlantic via the North Sea. The same was done with the addition of submarine nets and patrols in the English Channel. However, the need for British ships to operate in the channel to supply troops in Flanders made it difficult to stop U-Boats. Over 250 were able to get through the defenses in 1917.
It was well known via reconnaissance that the Germans were using the captured Belgian port town of Bruges at a base for their U-Boats operating in the English Channel. The British Admiralty looked at ways to destroy the threat. However, the U-Boat pens at Bruges were reinforced concrete and the British lacked any bombs that could penetrate them. Bruges was several miles from the sea and access to the ocean was granted by heavily fortified and defended canals that came out at Ostend and Zeebrugge. So no battleship could bombard the pens at Bruges without coming under fire from the strong coastal defense batteries. Even then the targets were too small for artillery of the time to hit. The same was true for the canal locks and gates. It was not until 1918 when the new head of the Dover patrol submitted an idea that a real solution came across the Admiralty's desk. If you could not destroy the U-Boats or the locks...you could block them.
Admiral Roger Keyes thought if you took some older obsolete Royal Navy ships and scuttled them at the canal exits that the U-Boats would be stuck in Bruges and rendered ineffective. Ostend would be easy but at Zeebrugge, the seawall had been armed to the teeth and would likely sink any approaching ships and repel any attempt. The seawall would have to be taken if there were any chances of success. But this meant an amphibious assault would have to be undertaken at the same time. More important would be to cut off any German reinforcements. In order to do this a submariner named Lt. Commander Sanford suggested ramming the viaduct that connected the wall with the mainland with an old submarine packed with explosives and blowing the bridge to prevent reinforcements. The plan was given the green light and several ships began retrofit while royal marines trained for the assault.
The main assault on the seawall prompted the selection of the old cruiser HMS Vindictive. It was a well armored and shallow draft ship that was needed for taking the seawall. It would take with it two heavily modified ferries with additional marines. All ships were modified with extra armor for their bridges and many machine gun and mortar emplacements were added to give the ships for firepower. Landing ramps were installed and an entire second deck was added the Vindictive to allow easier transfer of men to the seawall. Three older ships with skeleton crews were selected as scuttle ships. While Vindictive and its two smaller ships attacked the sea wall, the scuttle ships would come from a smoke screen and position themselves at the mouth of the canal and scuttle themselves. Coastal motorboats would then dart in and rescue the skeleton crews. It was a daring and audacious plan. It also required perfect high tide, on shore wind, and a new moon. Only 5 days a month fit the criteria. On St. Georges Day 1918 the raid set sail for Zeebrugge and Ostend.
When the Zeebrugge assault began at night with boats laying a thick smoke screen it took 3 minutes for HMS Vindictive to emerge from the smoke to hit the seawall. The German spotlights and guns immediately opened fire. The heavy seas make mooring the cruiser impossible but luckily one of its smaller companion ship pushed it against the wall and marines attempted to get onto the wall. The other ship could not get men on the wall with their ramps due to height difference and tried grappling hooks but failed. All three ships attacking the wall faced withering shell and machine gun fire. Adding to the woes a German destroyer was moored on the opposite side of the wall directly across from Vindictive and used its guns against the raid. At the same time however the submarine rammed the viaduct, evacuated its crew, and exploded vessel in just enough time to prevent German reinforcements from coming to the aid of the defenders on the wall.
At the same time the scuttle ships approached the mouth of the canal. The seawall had not been taken so its guns and those on the coast opened fire on them. One was so badly hit that it was scuttled prematurely, but the other two did make it to their assigned points and scuttled. The crews were evacuated by motor boats but a shell strike killed 150 in the evacuation. The HMS Vindictive pulled away ten minutes later and limped into the smoke screen and headed for home.
When the men came home they were welcomed as heroes. 11 Victoria Crosses (equivalent to the Medal of Honor in the USA) were awarded for the operation, the most in history for a single mission. It was a morale booster for the public and the war effort despite the fact the Ostend part failed and the Germans were able to clear Zeebrugge in a few months. But by then the war was turning and allied artillery and new convoy tactics were becoming effective against U-Boat operations in Belgium. It was not without cost though. The British suffered nearly 50% casualties (600 out of 1,300) men while the Germans lost 8 men with 16 wounded. It was a mission paid for in blood, but kept the fighting spirit of the Allies going in dark days.
Canal System of Bruges
Placement of Ships in the attack
Artist rendition of the raid in Popular Mechanics 1918
Viaduct damage from Submarine
Another shot of destroyed viaduct
The canal blocked by the scuttle ships