of the Royal Army Ordnance Corps (the predecessor to the Royal Electrical and Mechanical Engineers (REME)) made valiant efforts to recover and repair damaged ordnance and vehicles, thereby enabling many items to reach the coast. Similarly, the Corps’ main workshop was successfully withdrawn to the coast by its commanding officer, Lieutenant John Nicholson RAOC, who was awarded the MC for achieving this with the minimum of losses. Sadly, they then all had to be destroyed or abandoned.
Improvised jetty made by RE from abandoned lorries photographed by the Germans. IWM
In the months prior to the retreat the British Army had built up its resources and equipment and generally prepared itself for the impending battle. Royal Signals, for instance, made use of the French civilian landline network with Army personnel working alongside local staff in their exchanges. Wireless telegraphy was regarded as a back-up to the landlines, the network being reinforced by the laying of additional dedicated lines where necessary.
The hard lessons learned during the disastrous Norwegian and French campaigns made it immediately apparent that the procedures envisaged pre-war would have to be drastically rethought and that new techniques would need to be developed and applied. Principal among these operations were the importance of airpower, tactical mobility, close inter-service cooperation, rapid decision-making – and the need for modern equipment.
Defeating the Magnetic Mine
As Britain’s fate hung in the balance, a crucial engineering challenge was presented to Allied scientists: how to counter the menace of the mines sown on the bed of Britain’s shallow coastal waters by German ships and submarines or parachuted there by the Luftwaffe. So serious was the problem that the Port of London, then Britain’s busiest port, was nearly closed.
These mines were detonated by the magnetic field of a ship passing over them, and it is notable that before those 800 ‘little ships’ sailed from Kent ports to rescue the troops stranded in Dunkirk, they had to be ‘wiped’ by teams from HMS Vernon to make them magnetically neutral.
Sinkings off UK’s east coast September 1939–December 1940. Chatham Historic Dockyard
HMS Belfast. Now moored near Tower Bridge. IWM
The importance of the ensuing engineering feat was later expressed by one of its heroes, Commander Sir Charles Goodeve: ‘Although in the technical achievement the human effort was not in the same class as the radar or U-boat battle, it was the first technical battle in which we won a decisive victory over the enemy; but more important still, it was one which brought science fully into the war in the very early days.’
The earliest casualty of the magnetic mines, the SS City of Paris, was damaged on 16 September while among naval casualties before the end of the year were the battleship HMS Nelson, which was put out of service for nearly a year; the newly commissioned cruiser HMS Belfast, which broke its back and took two years to be repaired; the destroyer HMS Blanche, which was sunk; Captain Lord Louis Mountbatten’s ship, the destroyer HMS Kelly, which had her stern blown off; and the minelayer HMS Adventure, which suffered serious damage.
Caught unawares, and ignorant of how they operated, the Navy’s experts had to wait for mines to be dropped until they could be recovered and dismantled before they exploded. Two such mines were dropped by the Luftwaffe on the mud flats at Shoeburyness, Essex, in November 1939, and defused and dismantled by Lt Cdrs John Ouvry and Roger Lewis RN, and by CPOs Charles Baldwin and Archie Vearncombe of HMS Vernon. The pairs were awarded DSOs and DSMs respectively for their bravery.
Thereafter, it was generally possible for the mines that could be found to be recovered and made safe, although sometimes things went wrong, with tragic results for those attempting to defuse them. The Germans also sometimes used delayed-action mines or booby-trapped the fuse mechanisms, adding to the hazards faced by the naval defusing teams. Among naval officers engaged in such work was Sub-Lieutenant (Sp) Peter Danckwerts RNVR, who was awarded the George Cross for his bravery. Detailed accounts of the mechanisms involved (which he described as ‘a miracle of ingenuity’) are contained in Danckwerts’ biography.
Exploded view of magnetic mine fuse mechanism. Peter Varey
Solutions also had to be found to protect ships from the mines that had been successfully dropped on the sea bed. A variety of counter-measures were investigated as a matter of urgency, but the two systems developed by Lieutenant Commander Charles Goodeve FRS RNVR proved most effective and were widely adopted. The first was to develop a system of detonating the mines which did not damage the vessels involved, and the second was to demagnetise ships.
The former aim was achieved by the Double L Sweep, which involved two small wooden-hulled minesweepers towing a long loop-shaped buoyant electric cable between and behind them, through which strong electric DC currents were passed; the magnetic fields then induced in the sea were sufficient to detonate the mines.
Danckwerts, Professor Peter GC MBE FRS (1916–84)
The eldest son of Vice-Admiral Victor Danckwerts, who had seen action in HMS Kent during the 1914 Battle of the Falkland Islands and had been the Navy’s director of plans in 1940. He fell foul of Churchill when the latter was First Lord of the Admiralty and was removed from office, but later served in Washington before becoming second-in-command of the Eastern Fleet.
After schooling at Winchester, Peter Danckwerts read chemistry at Oxford before joining the Royal Navy in 1940. Having volunteered for special duties, he was assigned to undertake bomb and mine disposal.
After a short training period, S/Lt (Sp) Danckwerts RNVR led a small team defusing magnetic and other mines dropped in the Thames Estuary between Teddington and Southend. He was awarded the George Cross later that year for ‘great gallantry and undaunted devotion to duty’ whilst neutralising enemy mines.
In 1942 he was posted to Gibraltar to deal with the threat of Italian mines, including limpet mines attached to ships by frogmen riding midget submarines. Then, after a spell in Algiers, he participated in the invasion of Sicily but, ironically, he had the misfortune to tread on a small anti-personnel mine. After hospitalisation in Portsmouth, he spent the last year of the war with the planning staff at the headquarters of Combined Operations.
Following demobilisation, he studied chemical engineering at MIT and then worked as an academic in Britain before joining the UK Atomic Energy Authority. He was appointed professor of chemical engineering at Imperial College and then at the University of Cambridge. He was elected president of the Institution of Chemical Engineers in 1965 and a Fellow of the Royal Society in 1969. After retiring from the University of Cambridge in 1976 he became the executive editor of Chemical Engineering Science.
He died in Cambridge on 25 October 1984.
The demagnetising of metal ships was accomplished by degaussing the hulls of the ships. Initially this was done through a process known as coiling, which involved wrapping electromagnetic coils around the hulls and passing strong electrical pulses through them, thereby making the ships magnetically neutral.
