An acquaintance who has no small knowledge of military matters put the following to me recently:

‘We all have different perspectives and experiences and mine lead me to say this:

‘I suspect that you have a higher regard for the Swordfish than is justified. Surely the successes on Bismarck and at Taranto are obvious.

‘But second hand knowledge of anti-aircraft weapons present on Bismarck declare that the aircraft were too slow to be properly tracked and thus the defensive patterns were ineffective against the FAA crews.

‘Vastly technically superior aircraft (B5N and TBD) suffered appalling losses in similar attacks. Thus I put to you that successes by type, while not totally circumstantial, must be reviewed and filtered by tactical employments.

‘The Bristol Beaufighter, in its torpedo bomber mark, while twin engined, and not carrier borne, achieved great success in the Med potting lightly guarded cargo ships due to great tactics. Yet the superior Martin B26 and Mitsubishi G4M were shot out of the sky in the pacific as torpedo attack aircraft because they were employed against weapons systems designed to cope them.

‘The Ju88 employed in Norway, and although not carrier borne, achieved great successes similar to the Beaufighters of the Med.

‘It is my observation and conclusion, that tactical employment was the deciding factor on this despite the fluke successes of the Fairey Swordfish. It was simply too slow to shoot down.’

The Royal Navy Historic Flight‘s Swordfish LF326 flying at the Yeovilton Air Day in 2011

It’s true, I have a great deal of regard for the Swordfish. I like to think that much of this regard is not merely based on sentimentality. No piece of military hardware can be considered in isolation – all are part of a package involving personnel, training, tactics, availability, serviceability etc. and even wider considerations such as strategy and supply chain. There are, it is true, a lot of myths about the Swordfish, foremost of which is that it outlasted its successor, the Albacore. This is not strictly correct – yes, the Swordfish remained in frontline service longer than the Albacore, but not in its primary role as fleet torpedo bomber. (In some cases Swordfish lasted long enough to be replaced by the Albacore’s successor, the Barracuda). The longevity of Swordfish, like that of the Hawker Hurricane, was owed primarily to its arguably coincidental suitability for alternative roles once it had become obsolete in its designed role.

I should further qualify that in an ideal world, the Fleet Air Arm would never have gone to war in 1939 with the Swordfish, at least not in its primary role. My blog ‘A Recipe For Obsolescence’ points out the muddled and complacent thinking that left the Fleet Air Arm with such an outdated concept when other major naval air arms were equipping with modern stressed-skin monoplanes. This does not detract from the opinion I hold of the qualities of the aircraft or its crews, or the value of its contribution to the war effort – it’s just that it would have been far better to start the war with something like the Fairey Barracuda.

It’s arguable that the Swordfish was utterly obsolete at the beginning of the war, possibly even by the time it first equipped Fleet Air Arm squadrons. A fabric-covered biplane in an era of stressed-skin monoplanes. A top speed little faster than a WW1 SE5a. How could it have possibly contributed anything to the war effort? How could it possibly survive in a combat environment? How could it have hamstrung the most powerful battleship afloat and knocked half the Italian Fleet out of the war without an almost ludicrous measure of luck? A fluke, in other words.

A Swordfish from 810 Squadron, one of those that attacked the Bismarck, in a relatively rare landing accident

I can understand the assertion that the Swordfish was simply too slow for modern weapons systems to cope with. It is an attractive point of view. The most modern carrier-borne torpedo bombers in service at the time of the Bismarck’s last battle were capable of anything between 60 and 100 mph faster, while land-based torpedo-bombers such as the Bristol Beaufort were faster still.

It is my view though, that the Fleet Air Arm’s successes at Taranto and against the Bismarck can be put down to more than just luck, and even down to more than luck and good tactics (although both played a part). Moreover, at least part of the success can be put down to the qualities of the aircraft, and even good design.

Why did the Bismarck not shoot down any Swordfish?

The Bismarck was attacked twice by Swordfish after the sinking of HMS Hood. Once by aircraft of 825 Squadron, HMS Victorious air group, and once by aircraft of 818 Squadron, 810 Squadron and 820 Squadron, HMS Ark Royal air group.

The first strike, from the Victorious, resulted in one torpedo hit for the loss of no aircraft. The torpedo struck on the Bismarck’s main armour belt – accounts differ as to the extent of the damage it did, some sources suggesting that the strike displaced the armour, loosened the collision mats and exacerbated the flooding caused by the hit from Prince of Wales, reducing the vessel’s speed. Other accounts suggest that the torpedo hit caused only minor damage, and it was the violence of manoeuvring that loosened the collision mats. In any event, the reduction in speed allowed the chasing Ark Royal to approach within the range of her aircraft.

The Ark Royal’s strike managed another three hits, one on the stern which caused such damage to the rudder assembly that the Bismarck was essentially unable to manoeuvre, and could be caught by the chasing capital ships and cruisers.

There are a number of reasons why the Bismarck failed to shoot down any of the Swordfish. Some of those relate to the Bismarck’s anti-aircraft system. In some respects it appears it was indeed ‘too modern’. I am no expert in anti-aircraft armament, but it is often stated that the Bismarck’s flak directors were indeed designed for faster aircraft than a Swordfish. It is not clear how much of a problem this posed. It’s hard to tell why the Bismarck’s anti-aircraft defences were established with this obvious flaw, as when the ship was under construction and being commissioned, the Swordfish remained the chief British carrier-based torpedo bomber, and its planned replacement the only-slightly-faster Albacore. The only likely French carrier-based torpedo bomber was the even slower Levasseur PL.7, which had been in service since 1930.

Inadequate anti-aircraft defence

The Bismarck’s directors having difficulty in tracking low-speed targets would have been reduced by the low deflection of the approaching Swordfish. The lower the deflection, the less the importance of the director’s ability to predict the course of an approaching aircraft. The deflection on the approaching Swordfish, at least when they were on their torpedo run, would have been virtually zero. A Swordfish (unlike later aircraft) did not have a torpedo sight that calculated the ‘lay off, which meant they had to aim the correct amount ahead of the vessel to allow for forward movement. A pilot who flew Swordfish with 810 Squadron described this to me:

“The torpedo sight was a horizontal bar on a level with the pilot’s eye line. This held twelve flashlight bulbs equally spaced. The distance between two bulbs represented 5 knots at 1,000 yards. So if the target was travelling at 20 knots and not turning towards the aircraft, the lay-off was 4 bulbs. There were no aids to assist the pilot in assessing the range from the target or the aircraft height – only the experience of the pilot. We practised constantly on friendly ‘targets’ and we had a camera which recorded our dive and which stopped when we would have dropped the torpedo.”

The ‘office’ of the Swordfish. The aircraft was rudimentary by WW2 standards

The pilot described how the aircraft would attempt to induce the captain of the vessel under attack to commit to a turn before they launched the torpedoes, so they could better judge where the ship would be than if the turn was made after the torpedo was launched. Deflection is the friend of the aircraft when it comes to evading anti-aircraft fire.

A report by the Naval Air Department of the Admiralty in April 1944 compared three methods of attack. These were approaching and escaping parallel to the target ship’s course; the traditional method of approaching directly, roughly perpendicular to the ship’s course, and then turning away; and approaching directly and escaping by flying over the target ship. The report indicated that the parallel attack was in fact safer in almost all circumstances as the aircraft nearly always presented a higher deflection target. In fact, in the most typical case, the parallel attack was found to be approximately eight times safer than a conventional ‘straight in’ attack as the deflection was highest. (ADM 44/122)

Furthermore, it seems that the Bismarck’s heavy flak mountings tracked too slowly to engage aircraft that were closer than around 3,000 metres, so the issue of the Swordfish being too slow may be academic.

In any case, the speed of the approaching aircraft, this was only one of the problems that affected the heavy flak. The system was fitted out with two different types of mounting due to the non-availability of the preferred type in sufficient numbers, and which were not synchronised with each other. Moreover, the heavy flak had not been tested adequately, and the crews not fully trained. To add to the vessel’s problems, some of the guns had been sited badly, and had limited arcs of fire.

The Bismarck did not have radar-laid guns, although to be fair the first of these were only just being fitted to capital ships. The directors did, however, lack any kind of stabilisation that might have helped them in the rough conditions.

The 3.7 cm SK C/30 guns mounted on the Bismarck were semi-automatic. Rounds had to be hand-loaded individually, and it was a slow-firing weapon for anti-aircraft defence. These guns did have stabilisation, but it never worked very well and was dispensed with in later designs.

In short, while the Swordfish was an obsolete pre-war design, the same accusation could be levelled at the Bismarck’s anti-aircraft defences. This would be remedied on the Tirpitz when it was being constructed, and on other heavy units of the German navy.

It’s also worth noting that the Bismarck had been at action stations for a considerable period of time. The crews were tired, stressed and undoubtedly no longer functioning at the peak of efficiency.

Having said that, it’s not as though the anti-aircraft fire failed to hit any of the aircraft. In fact, aircraft from each of the first five sub-flights in the Ark Royal strike received some hits from cannon shells and shell spinters – one aircraft was perforated 175 times, and two members of its crew of three wounded. The Swordfish reported flying into heavy and seemingly accurate flak as soon as they broke cloud. By the time the sixth sub-flight was in a position to attack, the barrage was so heavy that two of the aircraft could not get close enough to attack, and one launched its torpedo from around twice the recommended distance of 1,000 yards.

Conditions

The other factor that made life much more difficult for the Bismarck was the conditions. This impacted in several ways. The first was the visibility. The low cloud meant that the Swordfish could approach the Bismarck while hidden until they were relatively close, cutting down the time that the flak would have to engage them. Moreover, the thick cloud enabled some of the aircraft to reposition for a more favourable attack when they found they were not in the optimal position, by simply flying back into the cloud.

Second, the sea state was extremely high, and the pitching and rolling movement this imparted to the Bismarck was considerable, adding further significant difficulties to the gunners’ task.

Third, the attacks were made at night, or in deep twilight – the Victorious’ aircraft attacked at midnight, the Ark Royal’s at 2047 the next day.

Finally, the Bismarck was manoeuvring hard to throw the Swordfish pilots off their aim – which had the same effect in its own gunners.

The crews and tactics

Early-war Royal Navy TBR (torpedo-bomber-reconnaissance) crews were generally very well trained. The aerial torpedo attack was the Fleet Air Arm’s chief weapon, and it was practised incessantly, with fleet manoeuvres allowing more realistic training and evaluation of tactics. Training was carried out first in low flying, then with concrete dummy torpedoes, then with practice torpedoes that were identical to the real thing apart from the lack of warhead (a smoke float was fitted to enable the recovery of the torpedo when its run had finished), and finally with the practice torpedo against a destroyer doing its best to avoid attack. (They would be set to run deeper than the practice vessel). This training would carry on at operational squadrons. Even though 825 Squadron was supposedly inexperienced, being a new unit and not having trained extensively together, the individual crews would have been well prepared.

This is in stark contrast to the torpedo squadrons in the US Navy, which hardly ever trained with torpedoes, simply making dummy runs and dropping smoke bombs to mark the release point. According to Alvin Kernan’s The Unknown Battle of Midway, many of the crews from the torpedo squadrons had never dropped a torpedo in training.

The standard pre-war torpedo attack was composed of several sub-flights attacking from different directions. This was done to split anti-aircraft defences and to help mitigate the defensive manoeuvring of the target vessel – in other words, if the captain attempted to ‘comb’ one torpedo attack by turning into it (making the torpedo pass ahead of the ship), aircraft in a different position would be better placed. This was aided by the poor visibility and low cloud base, meaning aircraft could work into a more favourable position out of sight of the Bismarck’s gunners.

The business end of the RNHF’s Swordfish LF326, showing the dependable Pegasus engine and a dummy 18″ torpedo

The potential benefits of a night attack were well understood in the Fleet Air Arm at the time, especially given the vulnerability of its aircraft in daylight. The attack on Taranto had amply demonstrated the possibilities. This kind of attack could not have been considered in daylight and good visibility by the Fleet Air Arm in 1940-41, whereas a more modern and powerful naval air arm, such as the Japanese one, could. In fairness, those more modern air arms would have found a night or poor weather attack more difficult to carry out.

The aircraft

It’s only fair given the nature of this essay to consider the qualities that the Swordfish itself may have contributed. First of all, it was able to take off, locate the Bismarck (barring one case of mistaken identity with HMS Sheffield), carry out an attack, locate their own carrier (for the most part) and land again, in appalling weather conditions, at night. It’s not at all clear that other, more modern aircraft would have been able to do that – during the Marshall-Gilbert raids in January 1942, TBDs from the USS Yorktown flew into bad weather and four ditched or crashed into the sea. An attempt at night landing on another occasion had similarly poor results.

The Swordfish’s tractable flying characteristics undoubtedly contributed to the ability of the aircraft to operate in rough seas, high winds and poor visibility.

In addition, the manoeuvrability of the Swordfish, even when loaded with torpedo, enabled the pilots to jink and weave while on approach to make the target harder to hit. More heavily-loaded monoplanes could not take such violent evasive action while approaching the target.

Some of the Swordfish were fitted with ASV radar, and this undoubtedly gave them an advantage in locating both the target and the home carriers after the raid. In fact, it gave the Swordfish a distinct area of superiority over its rivals in other air forces, albeit one that was much more appropriate in the poor weather and visibility of the North Sea and Atlantic than the Pacific.

Finally, the Swordfish proved to have excellent ‘survivability’. It had self-sealing fuel tanks, and a construction that meant cannon shells mostly passed through the structure without causing any damage. At the same time, its steel-tube construction was immensely strong – the aircraft was stressed to 9G to give an ample safety factor when landing heavily or manoeuvring.

The rear fuselage of Swordfish LF326 with fairing panels removed, showing the strong but open steel structure

Other examples

My questioner points to other examples where more modern aircraft fared less well than the Swordfish attacking the Bismarck. The two aircraft cited are the American Douglas TBD Devastator and the Japanese Nakajima B5N ‘Kate’.

The TBD is chiefly known for its role in the Battle of Midway, 3-7 June 1942. On 4 June, three squadrons attacked the Japanese fleet, VT-8 from Hornet, VT-6 from Enterprise and VT-3 from Yorktown. The fifteen aircraft of VT-8 were all shot down, 14 before launching their torpedoes. VT-6 and VT-3 both lost ten aircraft, with four and two aircraft respectively escaping. No torpedo hits were scored.

The Douglas TBD Devastator

The B5N was the most successful carrier-borne torpedo bomber of the first half of the war. However, although it was fast by the standards of its competitors (235 mph) and carried the most effective air-launched torpedo of any major navy, the ‘Kate’ was not invulnerable. Despite the almost total lack of warning before the attack on Pearl Harbor, five were shot down by anti-aircraft defences. During the attack on the Yorktown and Lexington in the Battle of the Coral Sea, nine ‘Kates’ successfully reached a position to launch their torpedoes, of which three were shot down by anti-aircraft fire, and another aircraft was shot down that had not released its weapon. As the war progressed, the ‘Kate’ found it more and more difficult to survive attacks on enemy shipping. During the American attack on the Marshall Islands in December 1943, the task group was attacked by seven B5Ns just as the Yorktown was launching a strike. All the Kates were shot down. Only one launched its torpedo, and that missed.

In each case, these were striking forces that were, superficially at least, technically far superior to the Swordfish forces that attacked the Bismarck and the Italian fleet at Taranto.

These situations are only superficially similar though. The TBDs at Midway were mostly if not all shot down by the Combat Air Patrol (CAP) fighters protecting the fleet, which were not available to the Bismarck. During the Battle of The Coral Sea, the TBDs had fared much better when they had fighter escort or attacked a target lacking fighter protection, such as the carrier Shōhō which was sunk by TBDs and SBDs. Reports from surviving pilots at Midway describe the AA fire as ‘very ineffective’, and suggest that most of the shells burst considerably over range. Furthermore, although the TBDs technically had a much higher top speed than the Swordfish, their approach speed was almost exactly the same. The reason for this was the torpedo used by the TBD, the Bliss-Leavitt Mk.XIII, which was very problematic early in the war. It was fragile and prone to malfunctioning, and therefore the pilots treated it with kid gloves. According to Kernan, (p.48) Lieutenant Commmader John C Waldron, in command of VT-8, instructed the squadron to fly ‘very slow, 80-100 knots, very straight and level’. The after-action report for the Battle of the Coral Sea from the captain of USS Yorktown highlighted that ‘our planes are forced to come in low and slow’, called for the immediate replacement of the TBD with the ‘torpedo planes capable of high speed, long range, ability to dive, and sufficient gun power for their own defense’, and insisted that unescorted torpedo attacks would be likely to be extremely costly.

The TBD had some armour but lacked self-sealing fuel tanks.

Of the ‘Kate’ aircraft that attacked the carrier group in the Marshalls, three were shot down by Lexington’s anti-aircraft guns and the rest by the escorting destroyers. But by 1943, capital ships had much heavier anti-aircraft armament than was common in 1941, and those of the Lexington were radar-laid. The carrier group also had the benefit of a screen of destroyers and cruisers adding their guns to the anti-aircraft barrage.

Nakajima B5N over Pearl Harbor

There are other cases where Swordfish, and comparable aircraft, were certainly not too slow to shoot down. During the Channel Dash (Operation Cerberus, when the battle cruisers Scharnhorst and Gneisenau broke through from the Atlantic to reach Germany), a flight of six Swordfish were shot down, three three by fighters and the other three by anti-aircraft guns on Scharnhorst/Gneisenau and their escort.

On another occasion, two Albacores (which were only marginally faster than the Swordfsih) were shot down by the anti-aircraft batteries on the Tirpitz during an attempted torpedo attack. During the Battle of Cape Matapan, the one Swordfish that scored a hit on the battleship Vittorio Veneto was shot down by its anti-aircraft guns.

Conclusion

It is necessary, I believe, to separate the qualitative aspects of the aircraft from their relative modernity. Some favourable qualities of aircraft tend to increase with modernity – out-and-out performance, for example, including speed, rate of climb and ceiling. Others do not, such as range, turn radius and reliability. Other favourable characteristics may be reduced with modernity, such as landing speed, docility and simplicity. In other cases, the aircraft may be rendered more or less valuable by other factors such as the available equipment and weapons, the efficiency of the crew and the tactics employed.

There have been other occasions when considerably outdated aircraft have proved effective in combat – in an extreme case, the ‘Bedcheck Charlie’ Polikarpov Po-2 biplanes that made night attacks on US air bases during the Korean War. They did considerable damage and proved very difficult to shoot down. This was in part because they flew too slowly for night-fighters to intercept them, and this was no more a fluke than the Swordfish’s successes in 1940-41.

The TBD was, overall, a poor design that did not make the most of its modern features. It sacrificed many of the qualities that a successful torpedo bomber needed, such as the ability to perform a steep dive into the target area to avoid having to spend too long in range of anti-aircraft fire, and to increase speed in the ‘danger zone’. It made sacrifices in range, weapon carrying ability and arguable aerodynamics in order to carry the Norden bomb sight for level bombing, a role the aircraft was never required to carry out. Moreover, the TBD’s poor qualities were exacerbated by the ineffective Mk.XIII torpedo and poor crew training. It may have been technically more advanced than the Swordfish, but it was not superior.

The B5N was in many respects a very good design. It took advantage of its modern features, adding speed but not losing most of the qualities required by a good torpedo bomber. It could approach the target at altitude, and while it could not dive near-vertically like the Swordfish, could easily glide at 30 degrees, and it could launch its torpedo at high speeds. It was even an effective level bomber, without compromising its primary role. However, the ‘Kate’ lacked self-sealing fuel tanks and, like most Japanese military aircraft of the time, was lightly built. This helped with speed, manoeuvrability and range, but meant hits by anti-aircraft fire were much less survivable. In 1941 it lacked radar. It was superior to the Swordfish in many respects (and undoubtedly a better design for the Pacific) but still lacked some of the qualities that allowed the Swordfish to press home an effective attack on the Bismarck and at Taranto.

All of these things taken in the round, the Swordfish was an effective frontline torpedo bomber in 1940-41 in the conditions which it was used. It was tough, manoeuvrable, and could be used in extreme weather conditions and at night. It could be fitted with radar and its torpedo was tough and dependable, if slightly slow. Its crews were well trained and capable of exploiting the strengths of the aircraft and its weapons. It is unlikely that more modern aircraft would have succeeded where the Swordfish did, but this has more to do with the conditions in which the aircraft was capable of operating, the abilities of its crews, and the availability of radar in the aircraft and the shadowing ships.

The design of the Bismarck’s directors in failing to allow for aircraft flying as slowly as the Swordfish may have hampered the ship’s anti-aircraft gunners, but it is by no means clear how much of an effect this had, and in any case there were many other factors at play. The Bismarck’s anti-aircraft defences were inadequate in a number of respects, but even so they were able to make life very uncomfortable for the attacking aircraft. In other episodes, similar anti-aircraft systems were able to shoot down at least some attacking Swordfish and Albacores, so this would not seem to be an insurmountable issue.

Overall, I do not believe the success of the Swordfish in 1940-41 can be considered a fluke – and moreover, the achievements of the aircraft in 1941-45 as an anti-submarine aircraft protecting Atlantic convoys, again operating in conditions that few other types would be able to, are worthy of considerable regard even if the Bismarck and Taranto are removed from the equation.