Bombs and depth charges at sea
(2_15)

Extract from: “Climate Change & Naval War,"pp. 59 - 68 Bombs and depth charges at sea (2_15) The theme    Bombing at Sea     Some Bombing Events in 1939    Depth Charging U-boats    Summary    LITERATURE

The theme

Review

While considering naval forces in action, one would primarily think of naval surface vessels fighting with each other with roaring canons in a sea battle with thousands of fountains of water springing up from the sea due to impact of shells hitting the sea surface, and of battleships opting to sink heroically in the rough seas along with their commanding admirals and soldiers. Even a layperson now knows that war at sea had already shown many other dimensions in the previous century itself. However, the general image of a sea battle demonstrates that fighting at sea can disturb water layer of quite a large sea area, e.g. Battle of Jutland (Skagerrak) in May 1916. 250 naval vessels gathered there and operated in an area of about 2,500 square miles. But neither WWI, nor WWII saw many such events. Warfare at sea came to rely more on sea mines, submarines and counter measures to meet the goals, i.e., sinking of ships. Concerning WWI: 5_13 and 5_14.


Means of warfare increased

With the start of WWII navies had a fairly new means at hand, i.e. aerial bombing of floating or submerged vessels and use of depth charges to hit submarines. Like the impact of sea mines, bombs and depth charges have a considerable impact on the status of seawater in affected areas.  Further, one should not ignore the third activity, i.e. shooting and shelling of fighter planes or bombers with all the firepower, coastal batteries, and vessels with guns had in their possession, as a preventive measure against being attacked or bombed. In the course of a war at sea, millions and millions of ammunition, ranging from small to big calibre, would inevitably hit the sea.

Compared with the potential abovementioned two means of bombing/shelling had developed during the war, their deployment at start of war in 1939 was more restrained. Parties to war were not very well prepared for using airplanes in naval warfare and depth charges to fight submarines when war commenced. While Britain managed to set up an effective ‘Royal Air Force Coastal Command’ to go for the German U-boats and to undermine German merchant shipping in North-West European waters fairly soon after the war had started (Lit.: Goulter)[1], Germans never managed to create an effective aerial wing for their navy. Existing German naval air force was small, poorly equipped and remained insignificant. German Navy therefore had to depend on the Luftwaffe and its Chief, Hermann Goering, who zealously exercised his command over all Luftwaffe units that might be compelled to support naval operations (Lit.: Goulter, p.37)[2]. Even though air forces of both warring parties were active from the first day of war, they did not play any major role in naval warfare in 1939. Such being the case, one might wonder how much this section of war machinery actively or passively contributed in ‘stirring’ the seas during the autumn season of 1939. Similar uncertainties existed with regard to the number of depth charges used and their locations. However, one thing became already very clear during the initial few months of war. Military forces had grown tremendously since last major war, viz. WWI, as if a breeze had developed into a hurricane.

As it is common knowledge, there exists a mixed layer of water at the surface of the seas, from a few meters up to a maximum of hundred meters depth, which is stirred by surface winds, However, military activities can turn huge sea areas into mixed layers quicker than winds.


Presentation

Impact caused to seas in a sea battle with bombardments by airplanes and firing by battle ships and coastal batteries can only be imagined. How many bombs and shells ‘stirred’ the sea? How much explosives blew up? How many missions were carried out? None of the above questions can be answered here in detail, as such information is rarely available. The first four months of war can be regarded as a mere ‘military warming up’ phase. It certainly was, as far as aerial warfare is concerned, even though aviation had made considerable developments since WWI.

The question remains as to what restraints or precautions should have been observed by participants in the war in order not to drive the winter weather into arctic condition? The answer is left to everyone’s own judgement.  

Bombing at Sea

Bomber planes usually could carry up to two tonnes of ammunition, which means that on each mission they carried with them bombs in denominations of:  either twenty numbers of 50 kg each, or eight numbers of 250 kg each or four numbers of 500 kg each (Lit.: Schmidt)[3]. A small anti-aircraft gun of 2 cm could fire about 200 shots per minute.  Guns and munitions of upto 20 cm could go on larger naval vessels. During the first two months of war, German pilots were ordered to attack only warships, but the order was soon enlarged to include merchant ships as well. The ‘Loewengeschwader’ of the Luftwaffe soon claimed to have attacked more than 200 war and merchant ships, sinking 46 of them with a tonnage  of 70,000  and severely damaging 76 ships with a tonnage of 300.000 (Lit.: Schmidt). Veracity of this claim cannot either be confirmed or refuted here. But as the British Admiralty admitted in December 1939, German planes had attacked 35 of its vessels within a period of three days, sinking 7 ships (NYT, 21 December 1939). Total number of bomber attacks against naval and merchant vessels, ports and near coastal installations might amount to many hundreds over the first 3-4 months of war, with thousands of bombs deployed in North Sea area alone.

Depth Charging of U-boats

How many?

Depth charging of submarines during WWII actually meant hunting down of German U-boats, either by air planes, surface vessels or specially laid mine barrages. When the war started, Germany had only 57 boats ready for service of which only 23 were fit to operate in the Atlantic. In England it was reported that 15-18 German submarines could have been out at sea (NYT, 4 September 1939). Although the number was small in the beginning and never more than a dozen boats were in the Atlantic or on missions elsewhere at any time during the first few months. The Royal Navy did not fear anything more than the U-boats. Even with a modest success of sinking more than 100 ships with a tonnage of 100,000, the Allies felt the threat by U-boats seriously and employed all means available at their command to fight this enemy, whether real or imaginary. Consequently thousands of charges could have been deployed day by day.


Care to be taken

The crews needed to be trained and familiarized in such exercises. Following case involving a Russian Naval vessel might illustrate such a situation: “(Russian) commanders of transport ships and torpedo boats were so much afraid of being attacked by a Finnish submarine in the Gulf of Finland, that they set off depth charges every 15 minutes or whenever an unconfirmed sighting of a periscope was reported, resulting in a total of 400 depth charges having been dropped by end of operation that day”, (Lit.: Van Dyke, p.54)[4]. Although other commanders might have acted in a more restrained manner, one can easily imagine that a large number of depth charges was being thrown over-board every day. During the first 6 months of war, about 4,000 attacks against U-boats are said to have taken place (Lit.: Hackmann)[5]. Every single attack could have meant dozens of depth charges in action.


A seaman’s story?

There were a number of stories circulating about use of depth charges in a variety of ways. Following is one example of such a story:

“It was rough. …we were investigating a U-boat off Jan Mayen Island. …the captain gave the order to fire. Eventually the after gun, which was in the gunner’s control, went independent firing and some rounds went away. But for us, who never had heard a shot fired in anger, the noise was more frightening than the bombs… We carried out asdic sweeps on Sunday 13 October (1939) with the occasional depth-charge attacks which provided us with plenty of fish, to the chef’s delight. On Tuesday we were supposed to have been successful in destroying the enemy….(In fact there was no ‘kill’.) (Lit.: Thomas, p. 21)[6]


Attacking pattern

The following procedure could have been adopted in attacking U-boats:

Some Bombing Events in 1939

For references (Lit) see attached Literature list below

The aim of listing of following events is to give a brief illustration of what happened in the first few months of WWII.  The military force unleashed was strong enough to change the weather conditions in Northern Europe so much that the coldest winter for 110 years could occur.  Considerable number of aerial bombs released over sea, together with other naval and military activities, like patrolling, shelling, anti-aircraft fire, bombing, dropping of depth-charges, and such other activities had turned the sea ‘up-side-down’. This could have significantly contributed to the emergence of arctic conditions Bomber pilots had reported that they were ‘greeted’ with fierce gunfire salvoes when they reached enemy flotilla or coastline, which made it difficult for them to practice a precise pointed bombing. From the ‘full picture’ only a few events and scenarios can be mentioned here.
4 September 1939: The First RAF raid by about 30 planes in separate groups targeted a fleet of Nazi naval vessels in the German Bight, (Wilhelmshaven, and  Brunsbuettel). One officer reported (NYT, 15 September 1939): “We were near the German coast when half a dozen enemy bombers came out to engage us. A game of hide and seek in the clouds followed…. Conditions grew worse and there was heavy rain for an hour…..(W)e made our land fall accurately and flew up the Elbe estuary until we sighted a number of naval vessels…..The enemy held his fire until we were almost over our targets. Then suddenly he opened every gun he could bring to bear on us. (The pilot described) the anti-air-craft fire ‘terrific’, especially from the larger warships, which seemed to carry seven anti-air-craft guns on either beam”. About seven RAF planes did not return to their home base.

The British air force attacked the German fleet at the North Sea entrance to Kiel Canal (NYT, 5 September 1939); North Sea - 54 Blenheims and Wellingtons of RAF Bomber Command are deployed without result against German warships sighted in the North Sea”. (Lit.: Rohwer, Chronik).

8 September 1939: A concentrated bombing attack on the heavily fortified German island of Sylt…. apparently was made today by, what one observer described, ten to fifteen planes. Anti-aircraft guns boomed and explosions indicated that bombs were being dropped”. (NYT, 9 September 1939).

27 September 1939;:“Nazi Planes Raid the British Fleet”; (NYT, 28 September 1939). “Yesterday afternoon in the middle of the North Sea a squadron of British capital ships, together with an aircraft carrier, cruiser and destroyers, were attacked by about twenty German aircraft. No British ship was hit and no British casualties were incurred. One German flying boat was shot down and another is reported to be badly damaged”, (NYT, ditto). “This attack was made by fourteen German land bombers, it is said”, (NYT, 29 September 1939). “Last Tuesday about twenty German planes attacked a British North Sea Patrol”, (NYT, 8 October 1939).

29 September 1939: “ ..six British planes were reported by the Germans to have attacked a German naval squadron near Helgoland today” (NYT, 30 September 1939). “Five out of 11 Hampdens (planes) are shot down by German fighters”, (Lit.: Rohwer, Chronik)

5 October 1939: “British submarine’s crew, bombed all day at bottom of the sea” (NYT, 6 October 1939). “In the first hour six depth charges sounded faintly and in the second hour the explosions, louder and nearer, averaged one every two minutes”,(NYT, ditto).

9 October 1939; “British cruisers hunting submarines in the North Sea (southern coast of Norway) today fought off German bombers, which attacked repeatedly. … The bombers attacked again and again today, and from the decks of the warships anti-aircraft guns blazed. “ (NYT, 10 October 1939). Also a German naval flotilla with more than a dozen ships (Lit.: Rohwer); while the British employed 12 Wellington bombers, the Germans sent almost 150 planes to the scene, without registering any success (Lit.: Rohwer). “The entire attack, according to the German version, lasted two hours. The first German air fleet opened a heavy attack from the east and the second followed from the northwest. The number of planes have not been revealed, but the Germans have not denied the British report that more than 100 bombs were dropped, …” (NYT, 13 October 1939).

10 October 1939; “Diving from a height of 5,000 feet and driven off by fierce anti-aircraft fire from multiple pompoms of a British cruiser squadron, German bombers battled for more than an hour in the North Sea yesterday until finally repulsed. ….In the first attack on the British fleet, it is said, the Germans used 500-pound and 1,000-pound bombs…. Lieutenant Frank described the attack, declaring he dropped a 1,000-pound bomb on the carrier”. (NYT, 11 October 1939)

11 October 1939: “Since the war broke out, Sir Kingsley said, the coastal command flew on reconnaissance, anti-submarine and patrol convoys a distance of approximately 1 million miles and provided escort for 100 convoys. Submarines were sighted by planes on seventy-two occasions and thirty–four times the planes were able to attack, he said”. (NYT, 11 October 1939).

17 October 1939: “Nazi bomb naval base in Scotland”. “About a dozen German planes yesterday …rained bombs on British naval vessels lying in the Firth of Forth near Rosyth, Scotland, …(NYT, 17 October 1939). Three ships are slightly damaged; two bombers are shot down (Lit.: Rohwer, Chronik). “The first two planes were chased away (by British fighters) from 4,000 feet almost to the surface of the water and then out to sea. Ten minutes later several British fighters ‘ganged up’ against a bomber over Dalkeith and sent it crashing in flames at sea. Another raider was destroyed fifteen minutes later; it also fell into the sea.” (NYT, ditto).

18 October 1939: “In a brisk battle in which twelve unidentified warplanes attacked six warships off the Netherlands island Schiermannikoog, it was reported today”.  “British and German planes battled again over the British naval base at Scapa Flow.” (NYT, 19 October 1939). Four German planes attacked ships in Scapa Flow, losing one plane. Training ship Iron Duke was damaged in the attack. (Lit.: Rohwer, Chronik).

21 October 1939: Nine German bombers bound to attack a British convoy off the Humber estuary are intercepted by fighter planes shooting down four bombers. (Lit.: Rohwer, Chronik)

5 November 1939: Extract from a British eye witness account: “Our outlook shouted, ‘Planes right ahead, Sir; three planes; they are diving, Sir’. Then things happened awfully quickly. Our foremost guns opened fire, with a roar that drowned everything. The muzzles were elevated almost level with the bridge and yellow flames sprang out, obliterating the shapes of the German machines swooping over the convoy. The sea leapt up in columns where their bombs were dropped.” (NYT, 5 November 1939)

7 November 1939:  The first sorties by German torpedo-carrying aircraft were flown against a British destroyer unsuccessfully, the torpedo missed the target. (Lit.: Rohwer, Chronik)

14 November 1939: Nazi planes bomb Shetland Island. (NYT, 14 November 1939)

19 November 1939: A German minesweeper is badly damaged, and a total loss due to depth bombs from another minesweeper off the island Sylt. (Lit.: Rohwer, Chronik).

22 November 1939: Three Royal air force planes send a Dornier (bomber) into the sea before it reaches coast. (NYT, 22 November 1939)

12 December 1939:  Eight RAF Whitely bombers attack German seaplane bases at Borkum and Sylt. (Lit.: Rohwer, Chronik).

14 December 1939: Twelve RAF bombers attack German warships in Helgoland Bight, losing six. (Lit.: Rohwer, Chronik).  “British Bombers and Messerschmitts fight; both sides lose planes in Helgoland battle” (NYT, 15 December 1939). Nazi claim ten planes have been shot down. (NYT, 16 December 1939).

17 December 1939: German bomber planes attack trawlers off the English east coast and sink 10 boats with ca. 3,000 tons. (Lit.: Rohwer, Chronik)

18 December 1939: Driven away from the English coast, two German bombers dived out of the clouds on the 487-ton British motor ship Serenity today, riddled her decks with machine-gun fire and then dropped 18 bombs until one struck her amidships and sent her to the bottom. (NYT, 18 December 1939)

18 December 1939:  Britons see German Raid: “Big bangs shook my house. I saw bursts of fire and clouds of smoke and flames from the direction of the ships three or four miles away. There seemed to be something burning on the water for a minute or two. It looked to me as though something was blown up and went up in flames”. (NYT, 18 December 1939, p.12).

19 December 1939:  ‘Air Fleets fight off Helgoland’. ‘34 down, say Nazi’. “The biggest air battle of the war occurred yesterday when British bombers encountered German pursuit ships over Helgoland Bight” (NYT, 19 December 1939). The loss is 12 planes out of 24 RAF Wellington bombers deployed. (Lit.: Rohwer, Chronik).

21 December 1939: “German aircrafts have attacked thirty-five vessels, including two neutral ships, in the last three days, the Admiralty announced tonight. Of the ships attacked, one coasting steamer and six fishing trawlers were listed as sunk.” (NYT, 21 December 1939)

Further reading: A detailed assessment of events is compiled about the Russian invasion of Finland during December 1939 Russia–Finnish war (2_41), from which the following two events are quoted:

13 January 1940: (Harold Denny reporting): One Soviet plane was destroyed spectacularly over Helsinki in full view of people watching from ground….the plane dived with its engine shot off to within 2,500 feet of the ground….We saw a flash of fire in the sky, blotted out immediately by a mushrooming blob of black smoke and then scraps of debris began falling. A moment later we heard a roar. What had happened apparently was that a Finnish anti-aircraft shell had hit the plane squarely blowing it into pieces and exploding its load of bomb (NYT, 14 January 1940). 400 Soviet planes flew over Finland yesterday, dropping 500 bombs. (ditto)

13 January 1940: Gulf of Bothnia. A minesweeper and two patrol boats dropped depth bombs in an attempt to cripple a Russian submarine, which had trailed the small Finnish steamer, Bore 1, through the international waters of the Gulf of Bothnia.  (NYT, 14 January 1940)  

Summary

Bombs and depth charges were not only employed at random since September 1, 1939. The weapons had been improved since WWI and their ability to ‘deliver’ precisely had reached new dimensions in warfare. Presumably tens of thousands of massive explosions had mixed-up the sea over a short period of time. Sea reacted swiftly by cooling out too early for the forthcoming winter season and arctic air could penetrate Northern Europe without facing resistance.  Thus it can fairly be concluded that war at sea had successfully modified the weather. Europe was back in the Ice Age, (2_11).

LITERATURE:

Goulter, Christina J. M.; ‘A Forgotten Offensive’, London 1955.

Hackmann, Willem; ‘Seek and Strike – Sonar, anti-submarine warfare and the Royal Navy 1914-54’, London 1984.

Rohwer, Juergen and Huemmelchen, Gerhard; ‚Chronik des Seekrieges 1939-1945’ Oldenburg/Hamburg, 1968. The material is also available in German under: --www.wlb-stuttgart.de (Marine), Württembergische Landesbibliothek, Stuttgart; and in English: Rohwer, Juergen and Huemmelchen, Gerhard; ‚Chronology of the War at Sea, 1939-1945’ London, 1992.

Schmidt, Rudi; ‘Achtung – Torpedos los!’, 1991.

Thomas, David A.; ‘The Atlantic Star 1939-45’, London 1990.

Van Dyke, Carl; ‚The Soviet Invasion of Finland 1939-40’, London, 1997.