“Unveiling the Secrets: How Innovations in Technology are Redefining the Future of Precision Weaponry”

On September 8, 1943, the Second World War took a dramatic turn as Italian Marshal Pietro Badoglio, who had just replaced a deposed Benito Mussolini as Prime Minister, announced an armistice between Fascist Italy and the Allied Powers. The following day, a large Italian naval fleet, on its way to counter the Allied amphibious landings at Salerno, was ordered to break off and sail to Malta to prevent its ships falling into the hands of Italy’s former German allies. Commanded by Admiral Carlo Bergamini, the fleet included three battleships – including the flagship Roma – six cruisers, and eight destroyers. Not knowing the details of the Armistice, Bergamini was reluctant to surrender in Malta, and instead set course for La Maddalena naval base on the island of Sardinia. On approaching the base, Bergamini discovered it had been overrun by the Germans, and instead ordered the fleet to Bône – today Annaba – in French Algeria. But as the fleet passed through the Strait of Bonifacio separating Sicily and Corsica, it was suddenly attacked by a flight of German Dornier Do 217 medium bombers of Kampfgeschwader 100. The bombers had actually been trailing the fleet for some time, but Bergamini had assumed they were the air cover promised him by the Allies. But by the time the Italian anti-aircraft batteries opened fire, it was already too late. At around 3:50 in the afternoon bombs slammed into Roma and the battleship Italia, causing extensive damage. Her boiler rooms flooded and her engines out of action, Roma became a sitting duck. At 4:02, another bomb slammed into her starboard side, penetrating her ammunition magazines and touching off an enormous explosion. The ship quickly capsized and sank, taking 1,253 of her 1,849 crew – including Admiral Bergamini – with her.

This engagement was a significant moment in the history of warfare, for the weapons that sank the Roma were not ordinary bombs but sophisticated radio-controlled missiles known as Fritz X. Though precision-guided weapons or “smart bombs” might seem like a recent innovation, this technology – like so many others – was actually pioneered during the Second World War. And while these weapons arrived too late to affect the outcome of the conflict, they forever changed the way modern warfare is waged. This is the fascinating story of the birth of the Smart Bomb.

German research into guided munitions began in 1938 in response to Luftwaffe experiences in the Spanish Civil War. During that conflict, pilots of the Condor Legion – a volunteer air force sent to assist Nationalist leader Fransisco Franco – encountered great difficulty hitting moving targets such as ships at sea. Much of this early research was headed by engineer Max Kramer of the German Centre for Aerospace Research or DVL, who began fitting regular aircraft bombs with radio-actuated control surfaces. The weapon that would eventually sink the Roma was based on the Ruhrstahl PC 1400, a 1400 kilogram unguided armour-piercing bomb intended for use against heavily-armoured targets like battleships and cruisers. The name “Fritz X” was derived from the PC 1400’s original nickname, but the weapon was also variously known as the Ruhrstahl SD 1400, the Kramer X-1, the PC 1400X, or the FX 1400.

Kramer fitted the PC 1400 with a set of four forward stabilization fins and a guidance system built into an annular “box fin” assembly at the tail of the bomb. This system contained gyroscopes to keep the bomb stable in flight as well as a set of spoilers that could be deployed into the airstream to control the bomb in roll, pitch, and yaw. These spoilers were controlled via a Strasbourg radio receiver whose receiver antennas were housed in aerodynamic plastic fairings mounted around the perimeter of the box fins. Aboard the attacking aircraft, the bombardier used a Kehl radio transmitter and joystick to guide the weapon visually to the target, a set of bright red flares in the bomb’s tail increasing its visibility. However, the primitive radio guidance system only allowed the spoilers to be set to “full up” or “full down”, requiring great skill on the part of the bombardier. The transmitter could be set to 18 different frequencies between 27 and 60 Megahertz, allowing multiple aircraft to drop bombs at once without their guidance signals interfering with each other.

The Fritz X became fully operational in the spring of 1943, with 750 being produced and deployed.

The weapon was only deployed by one squadron – Gruppe III of KG-100 Wiking – whose Dornier Do 217K-2 medium bombers were fitted with special bomb racks for the Fritz X and Kehl radio transmitter sets. Due to the glide angle of the bomb, attacks were typically made from an altitude of 5,500 metres and a minimum range of 5 kilometres, with the launching aircraft immediately decelerating after release so the bombardier could keep the bomb in his sights. From standard launch altitude and range, a skilled bombardier could theoretically make a maximum correction of 500 metres in the bomb’s range and 350 metres in its bearing and place 90% of bombs within a 30 metre radius of the aiming point. Those bombs that did hit were capable of penetrating 5 metres of armour – more than enough to sink a battleship.

The Fritz X made its combat debut on July 21, 1943 during a raid on Augusta harbour in Sicily. Several other attacks followed around the island, but no hits were recorded. The weapon’s first successful use was in August, when KG 100 sank a Royal Navy corvette and damaged another in the Bay of Biscay. On September 9, the unit carried out its historic attack against the defecting Italian fleet off Sicily, sinking the battleship Roma and badly damaging the Italia. Two days later, they attacked the Allied landing fleet off Salerno, barely missing the light cruiser USS Philadelphia but scoring a direct hit on her sister ship USS Savannah. The bomb penetrated the roof of C turret and detonated in the lower ammunition-handling room, severely damaging her hull, blowing out her boiler fire and killing 197 crewmen. Savannah languished, half sunken, for nearly six hours before her boilers were relit and the ship limped to Malta for repairs. On September 13th and 16th similar fates befell the Royal Navy light cruiser HMS Uganda and the battleship HMS Warspite when Fritz X bombs sliced through seven decks and exploded near the ships’ keels. Both ships were severely damaged and had to put into Malta for extensive repairs. Other ships damaged by Fritz X attacks off Salerno include the Dutch sloop HNLMS Flores, the British destroyer HMS Loyal, and the American merchantmen SS James W. Marshall and SS Bushrod Washington – though the latter two may actually have been hit by conventional bombs.

In early 1944, KG 100 was deployed against the Allied landing fleet off Anzio. By this time, however, the deficiencies of the Fritz X were starting to become apparent. The line-of-sight guidance system meant the launching aircraft had to maintain a straight, steady course over the target, making them highly vulnerable to fighter attack. The Fritz X also could not be deployed in anything but the lightest cloud cover, and was far less accurate in combat than in training; indeed, throughout the weapon’s deployment, only 30% of launches resulted in hits, while only one ship – the Roma – was ever sunk. Even worse, by the time of the Anzio landing, the Allies had figured out how to jam the Fritz X’s radio control system. At first, jamming had proved surprisingly difficult, since the Strasbourg receiver could be tuned to a variety of frequencies and was designed to ignore transmissions coming from ahead of – rather than behind – the bomb. However, British radio engineers soon discovered that by targeting the receiver’s intermediate frequency, the system could be effectively jammed no matter what frequency the Germans selected. The Type 650 jamming transmitter was first deployed aboard Allied ships at Anzio in early 1944 and succeeded in preventing the Germans from scoring any direct hits with the Fritz X. By the time of the Operation Overlord landings in Normandy in June 1944, radio jamming plus overwhelming Allied air superiority had rendered the Fritz X all but useless, and it was soon withdrawn from service.

However, the Fritz X was not the only guided air-to-ground weapon deployed by the Germans during the war. In 1939, the Gustav Schwartz Propeller Works designed a glide bomb to allow bombers to attack a target from beyond the range of anti-aircraft batteries. The bomb did not have an active guidance system, and instead was fitted with an autopilot to maintain a straight course to the target. In 1940, however, a team of engineers at aircraft manufacturer Henschel led by Dr. Herbert Wagner converted the Schwartz design into a powered, guided missile by fitting it with a rocket motor and the same Kehl-Strasbourg radio command system as the Fritz X. Known as the Henschel Hs 293, the weapon carried 550 kilograms of explosives but, unlike the Fritz X, had no armour-piercing capability and was designed for use against unarmored merchant and auxiliary vessels. To this end, the nose of the missile was fitted with a donut-shaped kopfring that, on impacting the water, ensured that the Hs 293 struck the target’s hull perpendicularly like a torpedo. The weapon was steered through the use of elevators and ailerons operated by electric solenoids and jackscrews; no rudder was fitted.

Thanks to its rocket propulsion, the Hs 293 could be used at greater ranges and lower altitudes than the Fritz X. Upon release, the Walter HWK 109-507 rocket engine slung beneath the fuselage ignited, delivering 5.9 kilonewtons of thrust for 10 seconds and accelerating the missile to a maximum speed of 960 kilometres per hour. This engine was powered by a highly concentrated hydrogen peroxide monopropellant decomposed into high-temperature steam by a sodium permanganate catalyst, and was originally developed as a Rocket Assisted Takeoff or RATO pod to help lift heavily-loaded transport aircraft into the air. Once the engine had burned out, the attack procedure was the same as with the Fritz X, the bombardier using red flares in the missile’s tail to guide it towards its target.

Development of the Hs 293 began in early1940 at the Luftwaffe research centre at Peenemünde on the Baltic – where many other advanced German weapons like the V1 flying bomb and V2 ballistic missile were also developed. The first unpowered drops took place between May and September, while the first powered flight was conducted on December 18. The weapon proved stunningly accurate, scoring a direct hit on the test target – a small barn – on only its second live firing. A derelict 5,000 ton ship just off the coast was used for testing, and was soon nearly obliterated by dozens of direct hits. Operators were first trained on a ground-based simulator, then allowed to make three live launches; most trainees scored direct hits on their third launch. The Hs 293 was first used in combat by KG 100 on August 25, 1943, successfully striking the British sloop HMS Bideford in the Bay of Biscay – though the warhead failed to detonate. Two days later, however, the squadron succeeded in sinking the sloop HMS Egret. Over the following year, Hs 293s damaged or sunk some 30 Allied ships, while in August 1944 they were used – unsuccessfully – to attack bridges over the Sée and Sélune rivers in Normandy – the first use of an air-launched standoff missile in military history. However, like the Fritz X before it, the Hs 293 was eventually rendered ineffective by Allied radio jamming and air superiority and was largely withdrawn from service in late 1944. The last recorded use of the Hs 293 was in April 1945, when a special unit of KG 200 attempted to destroy bridges across the Oder river to slow down the advancing Soviets. The attack was a failure, with no hits recorded.

Undeterred, the Germans investigated several ingenious methods for getting around the jamming problem, including converting the Hs 293 to wire guidance. The radio equipment was removed and a pair of streamlined pods added to the wingtips containing 18 kilometres of fine, 0.2mm piano wire. Similar spools aboard the launching aircraft carried a further 12 kilometres for a maximum range of 30 kilometres. Command signals from the bombardier travelled through the wires as they unspooled behind the missile, rendering it immune to radio jamming. Even more impressive was the Hs 293D, which featured television guidance. The Fernes Company, in collaboration with the German Post Office, succeeded in creating a miniature 224-line television camera and transmitter package called “Tonne A”, which measured 17x17x40 centimetres and weighed only 130 kilograms – making it ideal for mounting in the nose of a missile. While still vulnerable to radio jamming, this system allowed the attacking aircraft to take evasive action after launching the missile, as the bombardier no longer needed a clear view of both missile and target. However, the war ended before either weapon could see combat.

One final German “smart bomb” of note was the Blohm und Voss Bv-246 Hagelkorn or “Hailstone”, an unpowered glide bomb designed to attack the LORAN radio beacons used by Allied bombers for navigation. Designed to use as few strategic materials as possible, the Bv-246 had wings made of magnesite cement moulded around a steel spar and carried 435 kilograms of explosives. Carried aloft by a fighter aircraft like the Focke-Wulf Fw 190, the bomb was to be released up to 200 kilometres from the target, whereupon it would automatically home in on and destroy LORAN transmitters using a passive seeker device called Radieschen. Testing began in late 1944 at the Unterlüss Proving Ground in lower Saxony, but unfortunately the guidance system proved troublesome and only 20% of the test vehicles flew properly. However, when the V-1 flying bomb campaign against Britain proved more successful than anticipated, the Bv-246 was cancelled without ever seeing service. Nonetheless, it pointed the way toward modern anti-radiation missiles like the American AGM-45 Shrike and AGM-88 HARM.

But while the Germans were the first to deploy guided weapons in combat, the Allies were not far behind, and by the end of the war actually succeeded in surpassing German technology. In the now largely forgotten China-Burma-India theatre of operations, much effort was expended in disrupting Japanese supply lines by destroying bridges along the Burma Railway. However, these narrow wooden bridges proved challenging for airmen to hit, and much ordinance was wasted in unsuccessful attacks. In response, Major Henry Rand and Thomas O’Donnell invented the Vertical Bomb 1 or VB-1. This consisted of a conventional 1,000 pound general purpose AN-M65 “iron bomb” fitted with a special box-fin tail unit. This contained gyroscopes to stabilize the bomb in roll, a flare to increase its visibility, and a set of ailerons controlled by the bombardier using a BC-1156 transmitter and joystick in the launching aircraft. Unlike the Fritz X and other German guided weapons, the VB-1 had no pitch or range control and only be adjusted in azimuth – hence its eventual designation of AZimuth ONly or AZON. This meant that the bombardier still had to release the bomb accurately to ensure it did not fall short or long of the target, making it best-suited to attacking long, narrow targets like bridges.

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