When she was built, she was fitted out with ten quick firing (QF) 12-pounder guns and eight QF 3-pounder Hotchkiss light naval guns – and as was common with warships of this period, she was fitted with two submerged 18-inch torpedo tubes. Two further QF 12-pounder guns were subsequently fitted and the eight QF 3-pounder guns were replaced with six heavier 6-pounder guns.
In 1911–1912, in the run-up to World War I, her original but by now outdated 12-pounder guns were replaced by nine more powerful faster-loading QF 4-inch guns. A brand new design introduced in 1911, the new QF 4-inch light naval gun would become standard on most Royal Navy and British Empire destroyers during World War I.
Pathfinder spent the early part of her career with the Royal Navy Atlantic Fleet, before being transferred to the Channel Fleet, and then to the Home Fleet. As the opening shots of World War I were fired, she was attached to the 8th Destroyer Flotilla, based at Rosyth in the Firth of Forth.
Great Britain declared war on Germany on 4 August 1914, and Germany quickly scored some notable successes against Royal Navy warships with the laying of sea mines. HMS Amphion, one of the second Active-class group of improved scout cruisers, was sunk by a mine laid by the German auxiliary minelayer SMS Königin Luise, just two days into the war on 6 August 1914, off the Thames Estuary. The mine broke Amphion’s back and caused her forward magazine to explode with the loss of 132 crew. On 3 September 1914, the old torpedo gunboat HMS Speedy, built in 1893, and now converted into a minesweeper, hit a mine and sank in the North Sea, 30 miles off the Humber, whilst attempting to assist the minesweeper HMS Linsdell, a victim of the same minefield. But although there were losses to mines in the first month of the war, there had been no loss to a torpedo, and the Royal Navy did not fully understand, or accept, the threat to surface vessels from submarines.
As the war began, Britain began a naval blockade of Germany, intended to cut off her maritime war supplies and to prevent the Imperial German Navy from breaking out into the North Sea and Atlantic to attack British shipping. The only way Germany could blockade or interdict British supply shipping was by the new submarine weapon.
The German Navy was inferior to the Royal Navy in numbers of ships – and so, to reduce the numerical inferiority, Germany embarked on a submarine offensive intended to sink as many British warships as possible and even the playing field. Ten submarines were initially sent out to attack Royal Navy vessels.
The submarine campaign however did not go well for Germany at first. During the first six weeks of the war, two of her submarines were lost for little or no return in British shipping. But this was all about to change – and Pathfinder would have the misfortune of being the first British warship to be sunk by a locomotive torpedo during this submarine offensive.
The U 19-class submarine U 21 of III Flotilla and two other German submarines were tasked to raid British naval units in and around the Firth of Forth, where the major British naval base at Rosyth was established. The Firth of Forth is a wide expanse of water on the east coast of Scotland: Edinburgh and North Berwick sit on the southern shores of its narrower section as it opens out to the North Sea.
U 21 was under the command of the 29-year-old Leutnant zur See Otto Hersing, who would go on to sink 40 Allied ships, totalling almost 114,000 tons of shipping, as well as damaging two others. (After later sinking the pre-dreadnought British battleship HMS Triumph on 25 May 1915 and then the pre-dreadnought battleship HMS Majestic off Gallipoli two days later, on 27 May 1915, he became known as the Destroyer of Battleships by his colleagues. He would go on to survive the war, passing away in 1960.)
At the beginning of September, whilst approaching the Forth Rail Bridge in the Firth of Forth, the periscope of U 21 was spotted near the Carlingnose Battery, which opened fire without success. Hersing withdrew U 21 from the Forth and commenced a patrol in safer waters, from May Island southwards.
On the bright sunny morning of 5 September 1914, Hersing spotted HMS Pathfinder heading south-south-east, followed by elements of the 8th Destroyer Flotilla. At midday, the destroyers came about and began to head back towards May Island. Hersing watched as Pathfinder detached from them and continued her patrol to the south.
Later that afternoon, whilst at periscope depth, Hersing again spotted Pathfinder – this time she was returning to her base. With her endurance limited by her poor stocks of bunker coal, she was only making about 5 knots, to conserve her coal. A speeding warship was a very difficult target for any submarine to hit, but at this lumbering slow speed she presented a relatively easy and valuable target for Hersing.
At approximately 3.45 p.m., Hersing gave the command for a single torpedo to be fired.
Lookouts on Pathfinder spotted the torpedo track heading towards their starboard bow at a range of 2,000 yards. The officer of the watch, Lieutenant-Commander Favell, gave orders for the starboard engine to be put astern and the port engine to be set at full ahead with full helm. This should turn her bow to starboard as quickly as possible and allow her to comb the track of the torpedo, and avoid it.
The attempt to comb the track of the torpedo however failed – she was most likely unable to manoeuvre quickly enough given her initial slow speed of 5 knots. The torpedo closed at speed and then hit her just forward of the bridge. It is suspected that the torpedo blast may have ignited the silk bags of cordite propellant charges for Pathfinder’s main battery guns and caused a flash, because there followed a second, massive explosion within the fore section of the ship, as the forward magazine blew up. Any crew below decks in the forward section were killed instantly. The foremast and No 1 funnel collapsed and toppled over the side.
The bow section of the ship, on the other side of the explosion, sheared off and sank like a stone. Pathfinder gave a heavy lurch forward and immediately took on an angle down by the bow of about 40 degrees. Water came swirling up the ship and quickly began to envelop the bridge and searchlight platform. The command was given to abandon ship, but the stricken ship was going down by the bow so quickly that there was no time to swing out the lifeboats.
As the water-filled forward part of the ship sank quickly into the sea, the stern lifted up out of the water and a massive pall of smoke rose into the air. Although the huge explosion in Pathfinder had happened well within sight of land and should have been seen and heard, in an effort to attract attention as she settled into the water, her captain ordered the stern gun to be fired. The gun mount perhaps had been damaged by the force of the explosion, because after firing a single round, the gun recoiled and toppled off its mounting. It rolled over the quarterdeck and then went over the stern, taking the gun crew with it. A short time later, the ship disappeared from sight below the surface, taking most of her crew down with her.
One of the few survivors later recounted how he had been below deck when the explosion occurred. He quickly got himself up on deck, only to slide down the sloping deck and become jammed beneath a gun. He was carried underwater as the ship went down but managed to free himself and swim to the surface.
Fishing boats from the port of Eyemouth were first to arrive at the scene of the disaster, only to find an expanse of sea that was littered with the scattered debris of a ship’s passing and a slick of fuel oil. Clothing, bodies and parts of bodies floated on the surface amidst the debris.
In the distance, the two-funnel 350-ton destroyer HMS Stag and the 465-ton torpedo boat destroyer HMS Express both observed the plume of smoke from the explosion – and each capable of making 30 knots, they turned to steam for the scene. It is said that as one of the destroyers arrived on scene it had an engine problem, which turned out to have been caused by a dismembered leg in a sea boot blocking a seawater intake.
There were only 18 confirmed survivors from Pathfinder’s crew.
At first, the British authorities attempted to cover up the true cause of the sinking, fearing to reveal just how vulnerable to torpedo attack British warships were. The loss of Pathfinder was therefore at first reported as being caused by a mine, the Admiralty having already reached an agreement with the Press