A Forgotten Offensive

Royal Air Force Coastal Command's Anti-Shipping Campaign 1940-1945

Christina J.M. Goulter

• Publisher: Routledge
• Year: 2014
• Print ISBN: 9780714641478
• eBook ISBN: 9781135204617
• Edition: 1
• Topic: Geschichte
• Subtopic: Militär- & Seefahrtsgeschichte

The "forgotten offensive" of the title is RAF Coastal Command's offensive against German sea-trade between 1940 and 1945. The fortunes of the campaign are followed throughout the war, and its success is then evaluated in terms of the shipping sunk, and the impact on the German economy.

1

Lessons Learned: The First Maritime Aviation Experience

WHEN the First World War broke out, the aeroplane was in its technical infancy. A practical flying machine had existed for only a couple of years, but the impetus of war was such that by the end of hostilities in 1918, most of the problems associated with maritime aviation had been discovered, and considerable progress made towards solving them. Yet, in the time between the two wars, virtually nothing was done to advance the science of maritime aviation, so that the technology, in particular, with which Coastal Command entered war in 1939 was, in many respects, essentially the same as that perfected by the Royal Naval Air Service.

There are two principal reasons for this lack of progress. The first, and most important, was inter-Service rivalry and related predominance during the interwar years of strategic bombing doctrine, which over-shadowed other ideas on the employment of air power. The other factor was the amalgamation in 1918 of the Royal Naval Air Service and the Royal Flying Corps to form the Royal Air Force. The RFC, being the larger of the two air branches, dominated the new service, and hence lost sight of valuable research work and conclusions drawn from the RNAS’s four years’ operational experience. The Naval Staff, as a whole, had a positive attitude towards aviation, and their interest intensified in the course of the First World War, while the War Office demonstrated far less ambition. The contrast in approaches was evident from the start.

Before the war, budgetary constraint kept investment in aeroplane technology low, but while the War Office chose to save money by encouraging civilian aviators, in the Samuel Cody mould, to carry out the type of work in which it was most interested – reconnaissance and artillery spotting – the Admiralty undertook its own trials with aircraft built to its specifications by private firms. These firms also did much of the the needs of naval aviation distinguished themselves as pioneers, such as the Short brothers.¹

Aviation science advanced rapidly between 1909 and 1911, and the navy not only took advantage of developments but was, in many areas, at the forefront of research. Naval aviators were supported by an institution which had a strong tradition in research and development, particularly with regard to long-distance navigation.

By this stage, there were in existence a number of ideas on how best to employ the aircraft in the naval sphere. Some ideas were so visionary that it would take some years before technology had advanced sufficiently to enable concepts to be turned into reality. The first naval role envisaged for the aeroplane was coastal patrol. In conjunction with the warship and the submarine, the aeroplane was to keep Britain’s territorial waters free from hostile vessels. In this capacity, it was to act only as the ‘eyes’ of the Fleet; the aeroplane’s construction was not, as yet, sufficiently strong for the carriage of weapons. Hostile vessels would be reported on an aircraft’s return to base, and warships or submarines directed to the position of the sighting. Patrol times were limited by the aeroplane’s endurance, which permitted flights of between only 40 and 50 miles from shore.²

The question was raised as to the advisability and practicability of flying an aircraft from the deck of a warship. The first to contribute to the solution of the problem was Lieutenant C.R. Samson, one of the first naval officers to obtain the Royal Aero Club’s Aviator’s Certificate. Samson succeeded in making the first flight off a ship’s deck, in December 1911, and this broadened dramatically the scope of naval aeronautics. The aircraft could be carried right to the heart of any naval sphere of operation, and when acting as the ‘eyes’ of the Fleet, the time lag between sighting and engaging a hostile vessel with warships could be cut by at least half, as the engaging force would already be within 50 miles of the target.³

The implications of this led a submarine officer who held a Royal Aero Club Certificate, Lieutenant H.A. Williamson, to submit on 2 January 1912 a paper dealing with the value of shipborne aircraft in anti-submarine warfare. The paper demonstrated outstanding foresight and imagination, as the ideas he expressed were later developed successfully during the First World War, and many of the anti-submarine techniques he proposed had applications also in operations against surface shipping. Williamson’s suggestion that landing on a ship’s deck could be facilitated by the use of arresting cables laid the foundation for arrester gear, which has been employed on aircraft carriers since the First World War.⁴

The Admiralty expressed greatest interest in the main thrust of Williamson’s paper: the very great use to which aircraft could be put in not only detecting but attacking submarines and small surface craft. The paper drew attention to the advantages, especially in the saving of time, of having an aircraft carry out both scouting and attacking functions. Two aircraft, it was explained, could search the whole area enclosed in the 50-mile radius from a parent ship or land base in approximately two and a half hours. The type of coverage Williamson advocated was refined after war broke out two years later, emerging as the ‘Spider’s Web’ patrol.⁵

One month after Williamson submitted his paper, the Admiralty approved the holding of trials in order to establish whether submarines or small surface vessels could be detected easily from the air, and the degree of accuracy with which a bomb or other explosive could be dropped from an aeroplane in flight onto a moving vessel. Two trials were scheduled, one for June and one for September of that year, to be held at Harwich and Rosyth respectively. Appearing for the first time, at Harwich, was a bomb-dropping device designed by Commander Samson and Horace Short.⁶

The trials showed that more work was needed in bomb dropping and wireless telegraphy, but, in both fields, the research sanctioned by the Admiralty, or undertaken on the initiative of individual naval officers, appears to have been well in advance of any similar work conducted by the War Office in the same period. The apparent indifference with which the War Office regarded wireless telegraphy is puzzling given that it saw the aeroplane as being most useful in a scouting or reconnaissance role, and wireless offered an ideal means of conveying information quickly. It is difficult to trace in exact detail the wireless telegraphy and bomb-dropping experiments made by the War Office, but in reports before August 1914 little reference is made to work in relation to bombing, or signalling by wireless. On the occasions when they are mentioned, bomb-dropping and wireless telegraphy tests are listed under miscellaneous experiments. The level of experimentation undertaken by the Royal Flying Corps may be judged from trials carried out in May 1913 during which aircraft, flying at heights varying from 200 to 1,800 feet, dropped 2-lb bags of flour in tissue paper bags ‘to see if bombs …would hit the targets aimed at’.⁷ Even more significant is the possibility that the War Office turned down offers of assistance from the Admiralty in this area. This is suggested in a paper submitted to the Naval Staff from an armaments officer, who stated that he proposed to the military air Service that he would provide dummy bombs and bombsights if they wished to take up the subject of bomb-dropping.⁸ Apparently, no reply was received, and this was as late as August 1914.

The first recorded bomb-dropping experiment by a naval aviator occurred in March 1912 when Commander Samson dropped a dummy 100-lb bomb from a Short biplane at Eastchurch, and a series of similar experiments followed over the next two months. The Admiralty then asked the Ordnance Board to investigate further the dropping of bombs from aircraft, with particular reference to attacks on submarines and small vessels. A team of representatives from the Ordnance Board arrived at Eastchurch RNAS station, now the centre of naval aeronautics, in June 1912, and began work immediately with the object of designing bombs which would fall without somersaulting, and would arm themselves after being released from the aircraft. Also under investigation was a means of calculating the precise moment at which bombs should be released in order to hit a particular target. In other words, they sought a bomb-sighting apparatus.⁹

Not satisfied with the progress being made by the Ordnance Board researchers, in July 1913 the Admiralty appointed a naval gunnery Lieutenant, R.H. Clark-Hall, to head subsequent investigations. Clark-Hall, who between 1931 and 1934 was in charge of Coastal Command’s predecessor, Coastal Area, had an established reputation for work in aeroplane defensive armament, and he soon proved his worth. Mid-1913 marked the beginning of more systematic bombing trials, the most interesting of which occurred in December. Experiments were carried out at Eastchurch with grenades dropped from aeroplanes in multiple lots. This principle formed the basis of the ‘stick’ of bombs used first during the anti-submarine campaign two years later, whereby a collection of explosives was dropped in a line across a submarine, and later in bombing attacks on merchant shipping in Zeebrugge harbour in 1916, through to night operations by Halifax aircraft in the Skagerrak and Kattegat during the last eight months of the Second World War. By December 1913, the first functional bombsight was also undergoing trials at Eastchurch, and although it was of a very rudimentary design compared with those developed a few years later during the First World War, it nevertheless marked a major step forward in aviation science.¹⁰

During December 1913, the Admiralty created a section in one of its departments whose role it was to investigate aeronautical and related inventions so that its air service was kept at the forefront of the new science. One of the first inventions to be examined by this section was a bombsight designed by an officer of the Royal Navy, Lieutenant Travers. Its revolutionary feature was the automatic calculation of an aircraft’s speed in relation to a target. With earlier, more rudimentary sights, the calculation was made in part by the pilot or observer, while the aircraft was being flown either directly up or down wind. Further, the Travers Sight offered the option of dropping the bomb automatically; on arrival over the target an electric circuit was completed and the explosive device was released, or a signal was given to the pilot or observer that this was the dropping point. The sight remained in service, with various modifications, until the end of 1916 when it was superseded by a sight designed by another naval officer.¹¹

The effective application of wireless telegraphy in the sphere of naval aviation had also, in the meantime, forged ahead. In the spring of 1912, the first experiments were carried out with the aim of constructing a light-weight wireless set which could be mounted in the cockpit or observer’s cavity of a seaplane. During naval exercises in May, a Short seaplane was fitted with a simple form of transmitter, and radio signals were received by a number of naval vessels at ranges of between three and five miles. However, it was at Harwich in June 1912 during the first of the submarine versus aeroplane trials that tests with wireless began in earnest, and taking charge of this aspect of the experimental work was Commander Samson. He was able to report that during the course of certain flights at Harwich, he had been able to receive at the ground station messages very clearly at a distance of up to ten miles. A month later, the Admiralty decided that the full development of wireless telegraphy in naval aircraft necessitated at least one officer devoting all his attention to the subject.¹²

A similar pattern of development emerged with torpedo aircraft. Although beset with difficulties, the early experimental work carried out in the period 1912 to 1914 paved the way to success in the war. As with the use of bombs against submarines and surface craft, the Admiralty was receptive also to the idea of launching torpedoes from aeroplanes against vessels. In the first months of 1911, there were animated discussions among a number of naval officers concerning the employment of torpedo aircraft. At the head of this group was Captain Murray Sueter, who held the position of Inspector of Airships, and before this, a post in the Department of Naval Ordnance and Torpedoes. His interest in the application of aeronautics to naval warfare was as imaginative as his propagandising of it was energetic. With his naval experience and insight, he was quick to recognise the potential of aircraft as a long-range means of launching torpedoes against enemy ships, and submitted to the Admiralty a paper on the subject, along with one drawn up by one of his group. While no record exists of the Naval Staffs discussion of these papers, they must have met with general approbation, as the Admiralty called upon the aircraft manufacturer T.O.M. Sopwith to join a project to design a torpedo-carrying aeroplane.¹³

Sopwith, in conjunction with Admiralty draughtsmen, designed and built two machines, one of which was intended only for preliminary experiments. This non-flying torpedo aircraft made its debut at naval air station Calshot in the spring of 1914. The full nature and extent of experimentation with this machine cannot be ascertained from surviving records, but the importance that was attached to the work may be gauged from the following extract from the minutes of a meeting of the Committee of Imperial Defence Sub-Committee held on 25 June 1914:

The Chairman [First Lord of the Admiralty, Winston Churchill] said that the development of a torpedo carrying seaplane would greatly affect the value of this type of aircraft, and he hoped that in two or three weeks’ time it would be possible for a seaplane to fire a 14 inch torpedo, which would be sufficient to sink a small cruiser, a destroyer or a transport. The work had been practised for some time from a ‘mock up’ machine, and torpedo officers anticipate a high degree of accuracy. An order had been placed for a machine to carry an 18 inch torpedo.¹⁴

Trials with Sopwith’s torpedo carrier were a disappointment, however, and the honour of achieving the first flight with a torpedo slung from an aircraft went to another firm, Short Brothers, on 28 July 1914. Rivalry between aircraft manufacturers had provided an important impetus in the development of the torpedo-carrying aeroplane, but experimental work was at every stage under close scrutiny by the Admiralty. As First Lord, Churchill visited Calshot on 18 July on the occasion of the Review of the Fleet, and he took the opportunity to express his dissatisfaction at the rate of progress being made with regard to torpedo aircraft and suggested an increase in effort. Churchill was the leading exponent within the Admiralty of torpedo aircraft, and considered it the first really decisive weapon against surface ships to have appeared. At a meeting of the Committee of Imperial Defence Sub-Committee on 25 June, he agreed in principle that torpedo-carrying aircraft should be stationed at aerodromes 50 miles apart all along the coast for the purposes of detecting and attacking hostile vessels. One of the concluding points made by Churchill was that the naval air service would require fighting scout seaplanes to act as fighter cover to the torpedo aircraft, a suggestion which demonstrated great foresight in its appreciation that the heavier torpedo carrier would fall prey to hostile fighting aircraft. In a later generation of maritime aviators, during the first part of Coastal Command’s anti-shipping campaign, torpedo bombers were sent into attack without fighter cover. It required a casualty rate in excess of 20 per cent per operation among torpedo aircrews and nearly four years’ bitter and bloody campaigning before effective fighter cover was granted to anti-shipping squadrons.¹⁵

Whatever the role demanded of the aircraft in the naval sphere, whether reconnaissance, bo...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• List of Illustrations
• Editor’s Foreword
• Acknowledgements
• Preface
• Abbreviations
• Maps
• 1 Lessons Learned: The First Maritime Aviation Experience
• 2 The Ebb of Maritime Aviation, 1919–29
• 3 The Nadir of Maritime Aviation, 1930–39
• 4 Lessons Relearned: The Early Anti-Shipping Campaign, 1940
• 5 Survival Against All Odds: The Anti-Shipping Campaign in 1941
• 6 The Mounting Offensive, 1942
• 7 The Apogee of Maritime Aviation, January 1943–September 1944
• 8 Victory: Anti-Shipping Operations, October 1944–May 1945
• 9 The Verdict:
• Bibliography
• Tables
• Index