The WWI Air War over the Sea I

Although airmen’s attempts to liaise with the infantry during the war did not always achieve spectacular results, cooperative efforts between aviators and sailors proved far more impressive. At the outset of the war the British Royal Navy implemented a North Sea blockade to prevent merchant ships from reaching their destinations and keep the German surface fleet bottled up in port. The military and geopolitical effects of the blockade, though slow to show themselves, eventually proved effective, slowly bleeding Germany of resources, sapping the morale of the German people, and giving the United States a financial stake in Allied success. More narrowly, the blockade set the tone for the war at sea and for the next four years German naval activity in the Atlantic, the North Sea, the English Channel, and the air war over these waters centered on efforts to either break the blockade or, failing that, to inflict similar damage on the Allies.

Naval aviation differed significantly from its land-based counterpart in the way it interacted with the non-flying forces it supported. Military aviators regularly separated their reconnaissance missions from offensive operations, observing or photographing enemy activities that bombers or the artillery dealt with at a later time. Naval flyers similarly reported their sightings to nearby cooperating surface vessels, but the fleeting nature of floating targets frequently forced naval aviators to attack the targets they spotted immediately.

An American, Eugene Ely, demonstrated what the future held for naval aviation when he successfully flew an airplane off the deck of USS Birmingham in November 1910 and then two months later landed one on the deck of the Pennsylvania. The British created an Air Department within the Admiralty and began their own experiments in cooperation between aircraft and naval vessels in 1912, still more than two years before the beginning of the war. The duties naval aviators anticipated performing included scouting for the fleet using aircraft carried aboard ships, patrol work along the British coastline, and cooperative missions flown alongside defending flotillas and submarines. In January 1912, Lt. H. A. Williamson, a British submarine officer with an airplane pilot’s license, first proposed using aircraft to patrol against submarines. He hypothesized that, even if unable to attack, the aircraft’s presence would force a targeted submarine to stay completely submerged, thereby reducing its threat. Williamson noted the French were also experimenting with this idea. Later developments would prove Williamson’s predictions correct. Within six months early results of the British tests convinced the Royal Navy’s Submarine Committee that aircraft showed “promise of providing a valuable anti-submarine weapon.” On September 11, 1912, Capt. Murray Sueter, director of the British Royal Navy’s Air Department, submitted an aircraft development proposal to the Board of Admiralty in which he listed potential duties that included “assisting destroyers to detect and destroy submarines.” Sueter’s plan encompassed suggestions for a network of coastal air stations at various locations around the British coast, including Calshot, Dundee, Eastchurch, Felixstowe, Fort Grange, the Isle of Grain, Killingholme and Yarmouth. The Admiralty adopted Sueter’s scheme the following month and had most of the planned installations in operation prior to the outbreak of war. In response to the first successful U-boat attack on a British vessel, HMS Pathfinder, on September 2, 1914, the Navy beefed up the stations at Dundee and Killingholme. By the end of November the Navy implemented a revised plan specifically aimed at protecting the Straits of Dover, establishing bases to cover the fleet on both sides of the English Channel, in Dover, England, and on the French coast at Dunkirk. Earlier that same month the British introduced an offensive element to its air operations when a Royal Naval Air Service (RNAS) seaplane took off from Dunkirk to mount the first direct air strike on a German U-boat. Though the crew succeeded in locating the U-boat their attack failed when the submarine dived to escape. After this inauspicious beginning the Dunkirk crews devoted their attention mainly to reconnaissance and bombing of the German submarine bases at Zeebrugge and Ostend.

Lighter-than-air vehicles also played a role from the beginning of British anti-submarine operations. Gas-filled airships operating over the water offered the same endurance advantage that observation balloons held in land battles allowing aircrews to remain over their patrol areas hours longer than airplanes. By the summer of 1914 the Admiralty had taken over complete control of airship development excluding the Army, and in February 1915 Sir John Fisher, the First Sea Lord, ordered the construction of the SS (Submarine Scout) airship, the first lighter-than-air type specifically dedicated to anti-submarine warfare. The Admiralty’s goal in ordering SS airships focused especially on keeping open the Straits of Dover and access to the Irish Sea. Their apprehension proved well founded. By the spring, U-boats of the Deutsche Kriegsmarine (German War Navy) appeared for the first time off the west coast of Great Britain threatening receipt of western hemisphere imports. To offer political cover for its submarine campaign, Germany declared the waters around the British Isles a war zone, seeking to prohibit the area to any and all traffic, even ships representing neutral nations. Locating submarines in time to launch preemptive attacks required more speed and broader range than two-dimensional warfare offered, making aircraft crucial to defense. Submarines might be spotted cruising on the surface—time on the surface being necessary to recharge the U-boat’s batteries—or, in clear weather and calm seas, the boat might be visible even while submerged. By the end of the year, British constructors had built twenty-nine Submarine Scouts.

The amplified threat and the shift from two- to three-dimensional warfare required a broad reorganization of the entire naval defense system in order to incorporate the aerial component. As the war neared its first anniversary, RAdm. Sydney Freemantle, head of the Admiralty’s Signals Committee, categorized reconnaissance as the airship’s primary function, adding that its “duties are to locate enemy submarines and to keep them in sight as long as possible.” Successful communications between the airships and the Navy’s destroyers were clearly essential; to guarantee the strength of that link the Admiralty established special transmission and reception stations and proposed instituting a dedicated radio wavelength. The British Coast Guard administered the wireless stations reporting to each area’s senior naval officer or the Naval Centre. In August, in order to achieve tighter liaison between aircraft observers and the surface vessels whose attacks they would facilitate, the Admiralty removed all naval air stations from operational control of the director of the Air Department and placed them under the command of the various district senior naval officers.

During 1915, the RNAS concentrated on lighter-than-air craft for anti-submarine warfare owing to the “unseaworthiness of seaplanes and the general lack of heavier-than-air equipment and personnel.” Most of the airplanes and aircrew still in England remained unavailable for anti-submarine work, reserved instead for Royal Flying Corps training facilities. Those not tied up with training duties the RFC saved for home defense missions, thus protecting a nervous British public against the threat of zeppelin attacks on military targets and cities in the British interior. This allocation of resources reflected a new strategic approach to the defense of the British homeland. During the first months of the conflict responsibility for aerial defense of the United Kingdom had rested entirely with the Admiralty. In June 1915, acting on the recommendation of War Office Director of Home Defence Gen. Launcelot E. Kiggell, the chief of the Imperial General Staff divided control of home defense responsibilities. The Royal Naval Air Service stood accountable for attackers as they crossed the English Channel, and the Army’s Royal Flying Corps took charge once raiders had penetrated the coastline. Though shedding accountability for aerial defense of the mainland should have made more naval aircraft available for the war against the U-boats, division of control between the Army and the Admiralty and the transfer of naval air station command out of the Air Department to senior naval officers later in the summer instead exacerbated competition for these resources. The situation became further complicated by an increase in reconnaissance work over the English Channel and the North Sea that prompted the British to expand their Dunkirk Air Command. During the spring of 1916 the RNAS divided the command “into three wings, one for aerial reconnaissance, photography and control of naval gunfire, one for bombing and one for aerial fighting.”

Provision of bombing and aerial combat capabilities ensured that British naval aviators did not have to rely solely on passive defensive measures to combat the submarine menace. The highly mobile nature of the war at sea meant that naval aviators did not always have time to return to base or signal for help before their target disappeared. The Dunkirk group had already demonstrated the potential value of direct interdiction by launching some of the first aircraft attacks on U-boats at sea. Early in the war the Royal Naval Air Service organized an offensive capability, hoping to hit the enemy in his lair rather than simply waiting for his ships to appear. In its first month of operations, March 1915, Dunkirk crews launched bombing attacks on Ostend, Middlekerke and Hoboken, Antwerp, claiming (inaccurately, as it turned out) one submarine destroyed and two damaged. The naval airmen organized a combined air- and seaplane force some thirty strong utilizing seaplane stations on England’s east coast and a newly developed seaplane carrier, HMS Empress, with the aim of attacking German submarine pens across the English Channel. The group carried out several missions, but did not achieve significant success.

By the end of 1915 improved German antiaircraft defenses and the relative ineffectiveness of the light bomb loads early air- and seaplanes could carry caused the RNAS to forego further heavier-than-air offensive activity. Initially, airships appeared to offer an alternative, given their more impressive carrying capacity, but ultimately lighter-than-air bombers proved no more successful in achieving measurable submarine destruction than their heavier-than-air counterparts. Consequently, British airship crews returned to concentrating on reconnaissance, searching for submarines already at sea in conjunction with surface vessels rather than attacking the U-boats in their pens.

Despite the considerable attention historians have devoted to its bombing attacks on London throughout the war, the German Naval Airship Division devoted substantially more of its resources to reconnaissance than to destruction. Of the 1,497 sorties German airship crews mounted during the conflict, 971 (65 percent) had scouting over the North Sea as their purpose, compared to the 306 missions (20 percent) flown to drop bombs on England. The rather meager £1,527,544 total damage done to England during the German airship raids offers clear evidence that airship crews flying reconnaissance missions performed potentially far more valuable services.

Throughout 1916 and into the following year the British developed the Coastal airship, a larger design capable of longer patrols, and added to the number of stations dotting the United Kingdom’s shoreline. Between January and December, the RNAS constructed new facilities at Pembroke, Pulham, Longside, Howden, Mullion, and East Fortune, and opened an airship school at Cranwell. Reconsidering its earlier decision to abandon efforts to copy Germany’s successful zeppelins, the Navy resumed construction of a project previously cancelled, Rigid Airship No. 9, and built a large storage shed to accommodate the aerial behemoth at Howden. Anticipating further additions to its rigid aerial fleet in 1917, the Admiralty built more sheds at its Pulham, Longside, and East Fortune stations, and at the Cranwell training facility. Extending its reach off the British mainland the RNAS added an SS station at Caldale, in the Orkney Islands, for work with the Grand Fleet at Scapa Flow.

Despite these preparations and its early appreciation of aviation’s potential value in the anti-submarine war, not until the third year of the war did the Royal Navy give priority to the design and construction of heavier-than-air aircraft capable of directly attacking the U-boats. Until then neither the British nor the French felt any pressing need to rush. Germany’s desire to keep the United States out of the war had led the Kaiser to restrict the conduct of his U-boat commanders. This political strategy prevented submarines from achieving their full destructive potential and kept Allied naval losses within manageable limits during the war’s first two years. But by the second half of 1916 the German military and political situation had both eroded. Germany’s attempt to defeat the French at Verdun had failed, ending in nearly as many German casualties as French, a situation made worse by hundreds of thousands further German, French, and British losses at the battle of the Somme. In the wake of these setbacks, the Kaiser’s high command reorganized its military, naval, and aviation assets hoping that, by bold measures, they might defeat the French and British in whatever time remained before the United States entered the war. As a key component of this new strategy, the imperial government stepped up U-boat activity permitting the Kriegsmarine to return to unrestricted submarine warfare.

The lull in submarine activity in the Atlantic during the first half of 1916 had been prompted largely by American diplomatic protests. Germany’s failure to bring about a favorable resolution to the war at Verdun and the heavy fighting at the Somme brought home the prospects of eventual defeat. Balanced against the possibility of losing the war the political risk of offending the United States seemed one worth taking. U-boats resumed hunting prey in British home waters in August 1916 and the new threat prompted the British to expand seaplane patrols in September. In response, Adm. Stanley Cecil Colville, commander of the Royal Navy at Portsmouth, requested installation of a four-machine seaplane base at Portland to supplement the existing facility at Calshot and two more SS stations, one for the Isle of Wight and one for Portland, each with ten airships.

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