Special thanks to Daniele Notaro, who helped with information on the Nuclei Anti Paracadutisti.
The Autoprotetto FIAT 666NM was a project for a semi-Armored Personnel Carrier (APC) requested and autonomously produced by the Taranto Command of the Italian Regia Marina (English: Royal Navy).
It was proposed by the Taranto Royal Army command to help the Nuclei Anti Paracadutisti (English: Anti-Paratrooper Squads) units of the Italian Regio Esercito (English: Royal Army) to patrol the harbor and airport perimeters, defending the military infrastructure against Allied paratrooper sabotage and attack.
Unfortunately, the project was not finished due to bureaucratic problems and remained only at the prototype stage.
The Difesa Anti Paracadutisti
Given the extensive use of airborne forces during the Second World War, in 1941, the Italian Regio Esercito (English: Royal Army) created elite units to engage any Allied paratroopers.
In fact, by 1941, British parachute units had launched only a few missions (e.g. Operation Colossus of February 1941), but the German Fallschirmjäger (English: Paratroopers) had proved to be excellent assault units, despite the many losses suffered in the attack on Crete.
With Document Number 41224, ‘Potenziamento difesa Costiera e Piazze M.M., Protezione vie di Comunicazione ed Impianti, Difesa Antiparacadutisti’ (English: Enhancement of coastal defense and headquarters, protection of communication routes and installations, anti-airborne defense) of the Ufficio Ordinamento e Mobilitazione dello Stato Maggiore (English: Ordnance and Mobilization Office of the General Staff), the Italian Royal Army constituted 330 Nuclei Anti Paracadutisti with a total of 330 officers and 8,000 NCOs and soldiers.
The officers (second lieutenants or lieutenants) were all enlisted from veterans of other units, while some NCOs were young men from territorial defense departments and from enlisted troops already assigned to the Infantry or Bersaglieri (assault infantry). Each Nucleo Anti Paracadutisti was assigned to coastal defense divisions.
The Anti-airborne units were theoretically composed of 30 soldiers commanded by an officer, but the units were usually composed of fewer soldiers. In theory, they were to be highly mobile emergency response units that, having identified a threat in a short time, could quickly intervene to eliminate it.
With regards to the military equipment and the assigned personal weapons, most were delivered without problems, such as the expected 330 liaison motorcycles. There were delivery problems with the 660 Breda Modello 1930 light machine guns, of which not all were ever delivered, nor the 330 light trucks and 660 bicycles. For these reasons, the majority of the Nuclei Anti paracadutisti were equipped with trucks or guns donated by the divisions to which they were assigned.
In the Taranto area, the 241° and 243° Nuclei Anti paracadutisti (English: 241st and 243rd Anti-airborne Units) were deployed, assigned to the X Brigata Costiera (English: 10th Coastal Brigade), renamed in March 1943 to the 210ª Divisione Costiera (English: 210th Coastal Division) with some staff reorganization. This division had the task of defending the coastal perimeter between Taranto and Brindisi in the Salento area.
History of the project
Some of the Nuclei Anti Paracadutisti were deployed in the defense of harbors and Military maritime infrastructure, but the absence of trucks and vehicles forced the Regia Marina to donate some of its trucks and weapons to these units.
Some of the Nuclei Anti Paracadutisti units were assigned to the defense of the Taranto area. This city, situated in Puglia, one of the southern regions of Italy, was one of the most important harbors of Italy. The Comando in Capo (English: Headquarter) of the Regia Marina in Taranto assigned some of its FIAT 666NM to the anti-airborne units.
For their counter-attacks and anti-sabotage tasks, these units required better protected vehicles than simple heavy duty trucks. Thus, in June 1941, the Comando in Capo of Taranto delivered to the Ufficio dello Stato Maggiore della Regia Marina (English: Office of the General Staff of the Royal Navy) a project for armoring some of these trucks with 5 mm armored plates. This was made for two reasons: first, if a Nuclei Anti Paracadutisti was ambushed during a patrol, the armored vehicle ensured more safety for the soldiers carried on board. Secondly, an armored vehicle could support the unit’s counterattacks, which a truck could not do.
The Stato Maggiore della Marina or MARISTAT (English: Royal Navy General Staff) examined the project and, on 8th July 1941, authorized the production of a prototype, changing some of the specifications. In particular, they asked to reduce the armor, leaving the cab unarmored, removing the armored roof and adding slots for the use of personal weapons from inside.
After the modification of the project, the new vehicle project was ready in August 1941. The production of the prototype was assigned to the Arsenale Navale di Taranto or MARINARSEN (English: Taranto’s Naval Arsenal), which commenced to modify a FIAT 666NM.
On 8th September of the same year, MARISTAT wrote another letter, recommending to the Taranto headquarters to use special armor plates called ‘L.P.A.’ (unfortunately, nothing is known about this acronym). This probably referred to annealed, cold drawn steel. These were specially hardened armor plates produced by Terni Società per l’Industria e l’Elettricità (English: Terni Company for Industry and Electricity) foundry and could withstand 8 mm armor-piercing bullets. This request was accepted and officialized on 15th September 1941.
The FIAT 666NM (NM stands for Nafta Militare – Diesel Military) was produced by Fabbrica Italiana Automobili Torino or FIAT (English: Italian Automobiles Factory, Turin) from 1938.
The FIAT 666N was a heavy duty truck. Its prototype was ready at the end of 1938 and was presented to Benito Mussolini on 15th May 1939, on the occasion of the inauguration of the FIAT Mirafiori plant in Turin. The military version, the FIAT 666NM, was presented to the Centro Studi della Motorizzazione for evaluation on 19th September 1940.
It differed from the civilian version through the addition of acetylene headlights, a bulb horn, and manually operated turn signals on the sides of the windscreen. The first military order for 1,000 FIAT 666NM trucks was issued on 10th January 1941. Another 1,500 were ordered on 23rd July 1941, 1,000 on 5th March 1942, and 700 on 16th June 1943. In total, about 8,000 FIAT 666s left the assembly lines of the Mirafiori plant, including the post-war direct-injection 666N7 and FIAT 665NM versions.
The Regia Aeronautica (English: Royal Air Force) ordered 796 trucks on 23rd October 1941. This truck was used on the Eastern Front, in North Africa, in Italy, and in the Balkans.
The FIAT 666 was produced in a wide range of variants, such as standard truck and fuel carrier for civilian service, while for military service, recovery trucks, fuel and water carriers, mobile workshops, petrol engine variants, and many others were produced.
Engine and Suspension
Propulsion was provided by a FIAT Type 366 6-cylinder in-line diesel engine. It had overhead valves, with a displacement of 9,365 cm³ and FIAT-produced injectors. The maximum output was 110 hp at 2,000 rpm on the civil FIAT 666N, the FIAT 666NM for the Regia Aeronautica, and on the FIAT 665 NM. The maximum output power on the Regio Esercito’s FIAT 666NM was limited to delivering 95 hp at 1,700 rpm.
The maximum speed on-road was 57 km/h for the FIAT 665NM, 48.3 km/h for the power-limited FIAT 666NM, and 56.8 km/h for the FIAT 666N and FIAT 666NM. The fuel was kept in a 255 liter tank (135 liters for the FIAT 666N) located on the right side of the chassis, which offered a 750 km on-road range (465 km for the FIAT 666N).
As on the FIAT 626 medium truck, the engine could be extracted through the cab’s front after the removal of the grille thanks to rollers mounted on the two supports of the engine, rolling on guides fixed to the frame.
The single dry plate clutch was connected to the gearbox via a cardan shaft. This could be removed independently of the gearbox and engine simply by removing the rear casing. This meant that maintenance and disassembly were easier.
The transmission, thanks to the reductor, had eight gears and two reverse gears. The drum brakes were hydraulic and had a pedal-operated air brake booster. A 12-volt electrical circuit was used to power the headlights and dashboard, and a 24-volt circuit for starting the engine. The two 12V Magneti Marelli batteries were housed in a box on the left side of the chassis, behind the air tank.
The cargo bay measured 4.75 meters long by 2.20 meters wide, with a height of 600 mm on the civilian version and 650 mm on the military version. It was designed to carry up to 6 tonnes of cargo, but could carry, without much difficulty, a Carro Armato L6/40 light tank (weighing 6.84 tonnes).
The cab had the steering wheel and the driver on the right, while the vehicle’s commander was placed on the left. The cab’s doors opened backwards. Due to the slow production rates, some early FIAT 666NMs were equipped with civilian FIAT 666N cabs.
In spite of its respectable dimensions and its large load capacity, the FIAT 666 heavy duty truck had, with a chassis weight of 1 tonne and about 5 tonnes of additional structure weight, a total weight of 6 tonnes in case of the FIAT 666NM variant. Additionally, it could pull a 12 tonne trailer. Fully loaded, it was able to climb 26º slopes. Thanks to its short wheelbase and cab layout, it was comfortable traveling on mountain roads.
The FIAT 666NM had a wheel rim size of 20 x 8” (50.8 x 20.32 cm) and could use different types of tires all developed and produced by the Pirelli company in Milan.
Autoprotetto FIAT 666NM
Probably in late August or early September 1941, the Arsenale Navale di Taranto started modifying a FIAT 666NM with license plate ‘Regia Marina 0220’.
The modification was really simple. The workers of the arsenal took 5 mm thick armored plates of R.E. armor (unfortunately, nothing is known about this acronym) and welded them to a superstructure fixed on the truck’s cargo bay and side walls. The Arsenale Navale di Taranto had not used the ‘L.P.A.’ armor, as the Stato Maggiore della Marina had requested due the delays from the Terni foundry in delivering such types of armored plates. In order to not delay the production of the vehicle, it was preferred to finish the prototype with different armored plates.
On each side, there was an armored plate with a length of 4,080 mm, a height of 1,050 mm and 5 mm thick. These armored plates had four slits each, with a length of 300 mm and a height of 60 mm. The armored plate welded to protect the cargo bay’s front was 2,080 mm in length, 1,050 mm in height and 5 mm thick. On the rear, there were two openable armored plates, measuring 1,040 mm in length, 1,050 mm in height and 5 mm thick.
Unfortunately, due to the simplicity of the project, the cargo bay’s wooden sides were not protected by armored plates, leaving the 65 cm high plank walls without cover.
The vehicle could transport a total of 22 soldiers, including a driver and commander in the cab, seated on the right and the left side respectively. In the cargo bay, a total of 20 fully-equipped soldiers could sit on the original side wooden benches of the truck. Another two soldiers followed the truck on their bicycles and another one on the liaison motorbike.
In the original plan of the Headquarters of Taranto, the vehicle would have had a protected cargo bay (except for the roof) with armored plates with a height of 1,700 mm and also had a fully armored cab.
The absence of an armored cab would have made it impossible for the vehicle to support assaults by the anti-parachute units and would have made the driver and commander too vulnerable in the event of an ambush.
During the tests at the Taranto Naval Arsenal, it was found that the chassis and mechanical parts were not too stressed and the armored structure withstood the jolts of the truck during march without any problem. The problems that were immediately noted were the height of the armored structure, which raised the vehicle’s center of gravity, the absence of armor on the underside of the troop compartment (the Arsenal suggested putting sandbags under the benches to protect the underside) and, finally, the Arsenal informed the High Command that, due to the different plates of armor used, the vehicle could be penetrated by rifle or machine gun bullets from less than 100 meters away.
The report of the Arsenale Navale di Taranto about the production and testing of the prototype, delivered to the Stato Maggiore della Marina, also mentions production times and costs for the other 5 trucks ordered. Even though the order did not specify it, these were quite surely all based on the FIAT 666NM-RM version. The prototype’s production cost was 2,500 Italian liras (equivalent to the monthly wage of a lieutenant in the Regio Esercito). This included the cost of the steel plates, necessary workmanship and per-day wages of the workers who worked on the modification.
The arsenal also specified that, if the Royal Navy wanted to use ‘L.P.A.’ armor plates as suggested, the cost would go up to 18,300 liras for the materials for each truck. This was a total 54,900 liras for all the vehicles just for the plates. Taranto’s arsenal also claimed a total production time of 150 days (from the date on which the order was issued) for the delivery of all the vehicles.
Analysis of the Project
On 13th November 1941, Comando in Capo dello Jonio e Basso Adriatico (English: Headquarter of the Ionian and Lower Adriatic Seas) delivered a document to the Stato Maggiore della Marina about its own Autoprotetto FIAT 666NM tests.
The tests not only focussed on driving performance, but operational tests were also held, with mixed results.
In regards to the addition of sandbags which the Taranto arsenal had suggested, the Comando in Capo dello Jonio e Basso Adriatico explained that this was impossible because, in the space under the benches, the ammunition and hand grenade wooden crates of the soldiers transported on board were stored. This was a dangerous situation as it was, as they were exposed to enemy fire, with the risk of igniting a fire or an explosion in the transport compartment.
The slits were also a problem. They were useful to check the battlefield sides but were totally useless for the self-defense of the vehicle. The soldiers could not fire their personal weapons through them due to the limited space and their dimensions of 30 cm x 6 cm. Another problem was that the slits could not be closed by an armored hatch, so shrapnel or enemy bullets could pass through.
The absence of a slit on the front side of the cargo bay made communication impossible between the commander in the cab and the soldiers in the troop compartment.
The armored truck did not offer protection to the commander and driver in the cab, to the fuel tanks, or to the wheels.
The Comando in Capo dello Jonio e Basso Adriatico then suggested some changes. The same armored superstructure could be kept, but lowered in order to cover the cargo bay’s wooden walls.This solution would have led to better protection of the ammunition crates placed under the benches. It would also permit the crew to open fire with personal weapons and throw hand grenades over the top. However, this solution would have led to disadvantages as well. In this case, the plates would have protected only about one meter of the vehicle from the cargo bed, leaving the upper bodies of the soldiers poorly protected and would have made them vulnerable to ambushes from above. The primary purpose of the vehicle was to protect the Italian soldiers from ambushes, so this solution would have made the vehicle less useful.
Other suggestions were to try to protect the cab and the fuel tanks with the same armored plate thickness as used on the cargo bay, to add a communication door on the front side of the armored structure to allow the commander to communicate with the soldiers transported on board, and for the five production vehicles to use ‘L.P.A.’ armor plates produced by the Terni foundry to give more protection to the vehicle.
Nothing is known after the Comando in Capo dello Jonio e Basso Adriatico analysis. It is impossible to know if the Stato Maggiore della Marina accepted the modifications suggested by the Comando in Capo dello Jonio e Basso Adriatico or if the 5 armored trucks were even produced and delivered by the Arsenale Navale di Taranto. The issue was probably abandoned completely, due to high production costs and other priorities.
Even the destiny of the Autoprotetto FIAT 666NM per la Regia Marina’s prototype remains unknown. It was probably used, despite its deficiencies, by the Difesa Antiparacadutisti units in anti-paratroopers and anti-sabotage patrols until the Armistice of 8th September 1943.
The day after the Armistice, a British fleet transporting British paratroopers of the 1st British Airborne Division arrived off the coast of Taranto. Aided by Italian sailors in crossing the minefields around the port, the troops landed without encountering any resistance.
The Autoprotetto, if it was still in running condition, was not used and most likely soon dismantled or abandoned in some depot because it was no longer useful.
This project underlines the total absence of cooperation between Italian Army branches. In fact, after the experiences gained in the first months of war, the Italian Regio Esercito ground forces started half a dozen of projects of armored personnel carriers on various chassis, such as the small tracked Camionette Cingolate CVP-4 and CVP-5, the small wheeled T.L.37 Autoprotetto and other projects that remained only on paper.
The ground forces were also developing similar vehicles for infantry support and patrol tasks, which shared many features with the Autoprotetto FIAT 666NM of the Italian Royal Navy. These were the SPA Dovunque 35 Blindato and the Carro Protetto Trasporto Truppa su Autotelaio FIAT 626, which were under development already in May 1941, and the FIAT 665NM Protetto that was accepted in service in November 1942, a year after the Autoprotetto FIAT 666NM, but with which it shared about 70% of the chassis.
In order to have sped up production and decreased costs, it would have been enough for the Ufficio dello Stato Maggiore della Regia Marina to have asked the Centro Studi della Motorizzazione or CSM (English: Center for Motorisation Studies), the Italian department which was examining new vehicles for the Regio Esercito, about its undergoing developments, instead of introducing yet another parallel development.
The Autoprotetto FIAT 666NM was one of the dozens of unfinished projects started during the Second World War by the Kingdom of Italy. Unfortunately, it was not a brilliant project, its specifications were lackluster and the project would need more time and money to provide an adequate armored personnel carrier.
It represents how Italian units, lacking adequate vehicles and armament, were forced to find improvised solutions to better adapt to the situations in which they had to operate.
Size (L-W-H): ~ 7.095 x ~ 2.350 x ~ 3.850 m
Weight, battle ready: 8 – 9 tonnes
Crew: 2 + 20 (driver, vehicle commander + 20 soldiers)
Engine: FIAT Tipo 366 6-cylinder Diesel 9,365 cm³, with 110 hp at 2000 rpm
Speed: not specified
Range: not specified
Armament: unarmed but with slots for personal weapons
Armor: 5 mm on the superstructure on the cargo bay
Production: one prototype
Gli Autoveicoli da Combattimento dell’Esercito Italiano Volume II Tomo I – Nicola Pignato and Filippo Cappellano
Difesa del Territorio e Protezione Antiaerea (1915-1943) – Storia, Documenti, Immagini – Ufficio Storico dello Stato Maggiore dell’Esercito