20th April
The raid on Dover on 20 April 1917 was one of a series of fast, aggressive German naval strikes across the English Channel during the First World War. It was carried out not by large battleships, but by light, highly mobile forces designed to slip through British patrol lines, strike quickly, and withdraw before heavier Royal Navy units could respond. These raids were part of a broader German strategy to disrupt Allied shipping, weaken the Dover Barrage, and demonstrate that Britain’s coastal waters were not as secure as claimed.
The attack force was drawn from the German Navy’s Flanders Flotilla, based in occupied Belgium at ports such as Zeebrugge and Ostend. This force consisted primarily of large torpedo boats, which the British often referred to as destroyers due to their similar size and role. On the night of 20 April, a group of these vessels sortied into the Channel under cover of darkness. Their commanders aimed to bombard Dover and target the patrol forces guarding the narrow straits, particularly the Dover Barrage, a key defensive line of mines, nets, and patrol ships intended to prevent German submarines from entering the Atlantic.
The German force approached swiftly and with careful navigation through the hazardous waters of the Channel, avoiding mines and British patrols as best they could. Their tactics relied on surprise and speed. Once within range, they opened fire on Dover and its harbour installations. The bombardment itself was relatively brief but alarming, as shells landed in and around the port, which was a vital hub for troop movements and supply lines to the Western Front.
However, the Germans did not have complete freedom of action. The Dover Patrol, a mixed force of destroyers, monitors, drifters, and other small craft, was constantly on guard. Among the British vessels present that night was the destroyer HMS Swift, a fast and heavily armed ship designed for precisely this kind of engagement. Swift, along with other patrol units, moved quickly to intercept the raiders as reports of the attack came in.
The engagement that followed was confused and fast-moving, typical of night actions in the Channel. Visibility was limited, identification was difficult, and both sides relied on flashes of gunfire and fleeting silhouettes to locate their opponents. HMS Swift succeeded in closing with one of the German torpedo boats, identified as G85. In a dramatic and rare action for the war at sea, Swift launched a torpedo attack at close range. The torpedo struck G85, sinking it and marking one of the few successful destroyer-versus-destroyer torpedo engagements of the conflict.
This action demonstrated both the aggressiveness and effectiveness of the Dover Patrol when properly alerted. Despite the surprise of the German approach, the Royal Navy’s quick reaction prevented greater damage. Other British vessels attempted to engage, but the German flotilla, having completed its bombardment and recognizing the increasing risk of interception, withdrew at high speed back toward the Belgian coast.
The results of the raid were mixed. From the German perspective, it showed that their light forces could still penetrate British coastal defenses and strike important locations such as Dover. The psychological effect was significant, as it reminded the British public and military authorities that the Channel remained contested. However, the material damage inflicted on Dover was limited, and the loss of G85 was a notable setback for the attackers.
For the British, the action reinforced the importance of the Dover Patrol and the need for constant vigilance. The successful interception by HMS Swift was widely regarded as a tactical success and a morale boost. It also highlighted the challenges of defending the Channel: even with extensive minefields, patrols, and surveillance, fast enemy vessels could still slip through under the right conditions.
The raid of 20 April 1917 fits into a larger pattern of German naval activity in the Channel during that year, which included similar attacks on shipping and coastal targets. These operations were closely tied to Germany’s unrestricted submarine warfare campaign, as weakening the Dover Barrage could allow more U-boats to reach the Atlantic and threaten Allied supply lines.
In the end, the attack achieved limited strategic gains for Germany. It caused temporary disruption and demonstrated capability, but it did not significantly damage Dover’s operations or break the British defensive system. The Royal Navy’s response, particularly the action of HMS Swift, ensured that the raid would be remembered as much for its defense as for the attack itself, illustrating the ongoing cat-and-mouse struggle in the narrow and dangerous waters of the English Channel during the First World War.
