Beating the U-boat: How Trawlers Won the Great War at SeA
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- 7 days ago
- 6 min read
Cian Lynch | University College Cork
When one thinks of the warships that fought the First World War, images of colossal dreadnoughts and great armoured cruisers immediately spring to mind, battling for supremacy at Jutland, Coronel, or Dogger Bank. However, it was the humble fishing vessel that served the Royal Navy in the greatest numbers. Britain would call upon the crews of minuscule trawlers and drifters, which in peacetime towed fishing nets and used free-floating drift nets respectively, for its defence against the horrors of modern naval warfare, challenging these humble vessels and their motley crews of up-jumped fishermen to boldly sally forth to combat the U-boat menace in British and Irish waters.
For most of the First World War, Britain was subject to a submarine blockade as Germany’s lethal fleet of U-boats unleashed a campaign of unrestricted submarine warfare. Within a war zone around Great Britain and Ireland, merchant vessels could be struck by mine, torpedo, or shellfire without warning. In complete violation of international law and norms, even unarmed passenger liners were not spared this onslaught, nor were the neutral vessels that merely transited through Britain’s waters. The aim of this campaign was to destroy or frighten enough ships to prevent Britain from importing much needed food and raw materials, thereby starving it out of the war. Germany’s choice of weapons platform in perpetrating this campaign was the deadly U-boat, which could destroy even the largest of merchant vessels with a single torpedo or mine. Early in the war, SM U-9 proved their destructive capability by sinking three British armoured cruisers in an hour, taking almost 1,500 Royal Navy sailors to their watery grave in the process while SM U-35 gained infamy for sinking a devastating 224 ships throughout the war.
The Royal Navy, desperately short of suitable vessels to combat this novel and fearsome adversary, would call upon around 3,500 trawlers, drifters, whalers, paddle steamers, and a veritable menagerie of other assorted vessels. Around 54,000 men and boys were called upon to man these makeshift naval vessels to secure Britain’s vital lifeline of war matériel. For this herculean task, Vice Admiral Sims USN described how:
… the navy was impressing into service all the destroyers, yachts, trawlers, sea-going tugs, and other light vessels which could possibly be assembled; almost any craft which could carry a wireless, a gun, and depth charges was boldly sent to sea.
Skippers and crews entered the ranks voluntarily from the war’s commencement as officers, non-commissioned officers, and men of the Royal Naval Reserve (Trawler) and Royal Naval Volunteer Reserve. Though when conscription was introduced in January 1916, these skippers were impressed into these services rather than their talents being wasted in the army. Their vessels could be either hired, volunteered, or failing that, forcibly requisitioned in the case of 1,372 vessels.
In order to challenge the U-boats that lurked in the dark North Atlantic waters these small vessels would carry whatever armament could be spared to outfit them. Ideally, this would be a small 12-pounder or a 4” gun but sometimes it would be just a machine gun and rifles. As the war progressed, more novel forms of anti-submarine armament would be outfitted such as bomb throwers (a howitzer with a short range and a high angle of fire for attacking periscopes) and depth charges (a clever bomb designed to sink and damage the submerged U-boat), but throughout the war these small vessels could also deploy their nets to ensnare unlucky U-boats or indeed just ram the submersible if given the chance!
These versatile ships and their plucky crews were employed in a wide manner of roles to combat the U-boat menace. Trawlers made for particularly effective minesweepers due to their nature as vessels designed to tow heavy trawls and their wide, open decks allowed plenty of room for this treacherous work. Due to their great numbers, these small vessels were used to patrol key waterways throughout the war, with their shallow drafts allowing them to enter small harbours and inlets where conventional Royal Navy vessels could not, and to escort merchant vessels through the war zone later in the war. Drifters were used to tend antisubmarine nets which prevented the ingress of their stealthy adversary into harbours and stopped torpedoes from damaging moored ships.
Aside from their conventional military roles, the unassuming and unthreatening appearance of these small vessels also allowed them to act particularly effectively as Q-ships. These were warships disguised as civilian vessels intended to lure unwary U-boat commanders alongside. Guns would be concealed behind fake walls and crates while the crew would be disguised as unkempt, unruly sailors. This tactic was used to great effect by HM Armed Smack Inverlyon which, despite not even having an engine, sank UB-4 with nine rounds of its 3-pounder gun and a handful of rifles on the 15 August 1915, killing all the submarine’s crew in the process.
Another unconventional tactic was for trawlers to tow a lurking British submarine to surprise unwary U-boats that might approach a trawler to utilise its shells and bombs rather than its finite supply of torpedoes. When the U-boat was within range, the British submarine would slip its tow and fire at the unsuspecting U-boat; This only succeeded twice, with HMT Taranaki and HMT Princess Louise succeeding in this daring tactic. The case of HMT Taranaki’s success on the 23 June 1915 was an example of overcoming incredible odds; The British submarine’s tow cable failed to release, forcing Taranaki’s quick thinking crew to distract their unwary adversary by feigning abandonment while the submarine, C-24, fired a single torpedo to sink the U-boat. Not long afterwards on the 20th of July HMT Princess Louise and the towed C-27 succeeded in obliterating U-23 with two torpedoes. The first narrowly missed, the second struck home, killing twenty-seven of its thirty-seven strong crew.
Trawlers and drifters in Royal Navy service succeeded a handful of times in damaging or indeed destroying U-boats, clearly proving their worth despite their generally limited capabilities. Ten U-boats were sunk or captured by trawlers, drifters, and other small vessels. On the 30 April 1918, HMD Coreopsis bested UB-85 in a ‘David versus Goliath’ incident of a thirty-six-man U-boat with an 88mm gun and torpedoes surrendering to a slow, tiny 12-man drifter with a 57mm gun. Almost two years to the day earlier, on the 24 April 1916, HMT Telesia and HMT Energic would together sink UB-13 using mined nets, while U-14 would be lost to a furious barrage of shells from HMT Oceanic II and HMT Hawk about a year before on the 5 June 1915.
Aside from the more tangible successes of trawlers and drifters in sinking U-boats and escorting vessels to safety, they also succeeded strategically in what we would call anti-access/area denial (A2/AD) in modern military parlance. By their presence in great numbers, despite their limited capabilities, these minuscule vessels and their plucky crews played an outsized role in limiting the freedom of action that U-boat commanders had, thus limiting their ability to inflict destruction on Britain’s fragile supply lines.
The valiant efforts of Royal Navy trawlers and drifters came at a high price. Despite only sinking a handful of U-boats, around 400 trawlers and drifters would be lost during the war. The heroics of these brave mariners merited Victoria Crosses, Distinguished Service Crosses, Distinguished Service Orders, and many other decorations throughout the war, a small token for immense danger that they willingly faced in combatting much more capable adversaries in order to secure Britain’s supply lines and to sustain the war effort.
Further reading:
Steve Dunn, British Naval Trawlers and Drifters in two World Wars (Seaforth Publishing, 2021).
Roy Stokes, U-boat alley: The U-Boat War in the Irish Channel during World War I (Compuwreck, 2004).
Hew Strachan, The First World War (Simon and Schuster, 2006).
Paul Halpern, A Naval History Of World War I (Naval Institute Press, 2012).
Karl Brady et al, Warships, U-Boats & Liners (Irish Stationery Office, 2012).
Cian Lynch is a PhD student in University College Cork’s School of History. His current area of research is commerce raiding in the First World War, but he has an interest in contemporary defence and security, International Relations, and maritime history more generally. Cian currently serves as a Lieutenant in the Irish Army Reserve.
Twitter/X: @cianmlynch
