Sinking of HMS Pathfinder

On 5 September 1914, off the east coast of Scotland near St Abbs Head, the German submarine U-21 sank the British scout cruiser HMS Pathfinder. She was the first Royal Navy warship sunk by an enemy submarine, and also the first ship in history sunk by a self-propelled torpedo fired from a submarine.

Hunting at the entrance to the Firth of Forth

Pathfinder, built in 1903–1905 by Cammell Laird at Birkenhead, was a fast, lightly armed cruiser designed to lead destroyer flotillas. At the beginning of the war she led the 8th Destroyer Flotilla, based at Rosyth in the Firth of Forth.

At the beginning of September U-21, under Kapitänleutnant Otto Hersing, crept into these waters to hunt British warships. According to some accounts Hersing even sailed deep into the firth, as far as the famous Forth Bridge, and the crew of a coastal battery fired without effect at the periscope protruding from the water. U-21 then withdrew to the open sea and patrolled the coast south of the Isle of May, which lies at the entrance to the firth.

A few minutes

On the afternoon of 5 September Hersing sighted through his periscope the lone Pathfinder, returning from patrol. At about 3.45 p.m., from a range of roughly 1.8 kilometres, he fired a single torpedo. Lookouts on the cruiser spotted the torpedo’s track, but the evasive manoeuvre came too late. The torpedo struck beneath the bridge, and its explosion set off the propellant charges in the forward magazine. A huge blast tore apart the bow section of the ship, which broke in two and sank within a few minutes. There was no time to lower the boats.

The losses are hard to establish, because it is not known exactly how many people were on board. About 260 men died. The press of the time reported that several dozen had been rescued, but according to more recent research only about twenty sailors survived the disaster. Among the survivors was the ship’s captain, Captain Francis Martin-Leake. The column of smoke over the scene was seen from the shore, and the survivors were rescued by, among others, fishermen from nearby Eyemouth.

A new weapon

The Admiralty at first announced that Pathfinder had struck a mine. It probably did not want to admit that submarines, then regarded as an unproven weapon, were capable of sinking a surface warship. Eyewitness accounts, however, quickly reached the press. A month earlier, in August, it was the British who had scored the first success against the U-boats, when HMS Birmingham rammed U-15. Now the Germans had shown that their submarines were dangerous even to warships on the high seas.

Just two weeks later, on 22 September, another U-boat, U-9 of Kapitänleutnant Otto Weddigen, sank three old British armoured cruisers in little more than an hour, killing almost 1,500 sailors. Otto Hersing became one of the most famous German submarine commanders. In May 1915, off Gallipoli, he sank two British battleships, HMS Triumph and HMS Majestic.