Citröen U23 (1935)
 c1,000,000 built (civilian and military 1935-69)
 
Not as famous as the prewar Citröen Traction Avant or postwar 2CV and DS, the Citröen Type 23 was nevertheless the working horse of the French Army in May-June 1940 after some 13,000 were delivered, when ordered in emergency by September 1939. This solid design emerged in 1935, designed by Flaminio Bertoni as a general purpose 1.5 tons 4x2 truck. Far more were made for Civilian service (perhaps as much as a million until 1969, completely restyled in 1958). In 1940 alone, there were some 200,000 vehicles, in civilian and military service. Some 6,000 were captured and reused by the Germans, added to more than 7,000 produced into improved variants until 1944.
The U23, core of the French truck fleet
Origins
The Citroën T23 was originally a van, approved at the Mines Network, on April 25, 1935, with a gross vehicle weight (GVW) of 2,300 kg. It was presented at the Paris Motor Show in October of the same year alongside the brand's vans and heavy goods vehicles.
The Type 23 U series (or T23 U series) had a payload of 1,500 kg in the flatbed version, which gave it a gross vehicle weight of 2,300 kg (hence its designation "23," with "U" standing for "Utility" (vehicle)). Initially, Citroën imposed a single wheelbase of 3,380 mm to avoid the footprint tax introduced by Article 60 of the law of February 28, 1933, which affected all vehicles with a floor area exceeding 10 m² or 2 m in width. This is why the T23 measures 1.96 m wide and 5.00 meters long, 5.080 mm exactly overall with the tolerance on the accessories.
Development
The U23 (or Type 23), was a light (2-ton) truck unveiled by Citroën in 1935. The engine cowling and front body were borowed from the famous 
Citroën Traction Avant. This truck had a conventional rear-wheel-drive layout and was equally popular as the Traction Avant. Production started bodies in 1935 with many lasted through 1969, and approximately one million were produced. It was powered by a 1911cc 4-cyl. petrol engine with a 1,767 cc 4-cyl. Diesel engine, made available in 1936, 42-52 ch.
The 23U used a modern engine for the time, the same 11 hp sported by the famous Traction Avant, mounted with the gearbox reversed toward the rear, driving a driveshaft and a rigid axle with semi-elliptical spring suspension, as well as a right-hand rotation for the crank. The specific gearbox had three very short ratios, carrying the truck's load without straining the engine, plus a direct drive. The Type 23 thanks to all of this, and a well balanced and relatively low chassis, could reach 70 km/h.
The Citroën Type 23R had of coourse Michelin tyres with deep serrations for better grip. Its cab was derived from the front end of the "Rosalie" designed by Flaminio Bertoni. The Type 23 Di was unveiled at the 1936 Paris Motor Show. It had a 1,767 cc 4-cylinder diesel engine (40 hp at 3,650 rpm), and was launched on the market from February 1937, still with a payload of 1,500 kg. The engine was then a genuine Citroën diesel built under Ricardo license.
The Type 23 in the Military

Outside many civilian applications, the major customer was the French military. In 1939, the French army urgently ordered more than 13,000 Type 23Us for its needs, notably with specific military accessories such as towing hooks, and extended running boards with special side storage bins. The first examples were still equipped with curved and beveled fenders forward, but from the end of 1939, flat fenders appeared as they were simpler to manufacture.
The French Army ordered indeed large quantities of Type 23s from September 1939. They saw action in the summer of 1940 and at the time of the German invasion in May, it is estimated some 12,000 were active in many units, all arrived within ten months and about 1000 more until the armistice. Many were captured afterwards under German ocupation. Half of them, some 6,000, were pressed into the Wehrmacht, but many continued in civilian service, and there were derivatives such as the Bus and coach versions, called the Type 23 RU, were introduced in 1941.
Design
The Citroën Type 23 was designer by Flaminio Bertoni, a famous Italian designer (born January 10, 1903 in Masnago, Italy, died February 7, 1964  in Paris, France), and renown coachbuilder. He signed legendary models for Citroën such as the Traction Avant in 1934, 2CV (TPV 1937), H van (or "tube" in 1947), the DS, and the Ami 6.
The forward face indeed strongly recalled the Traction Avant, but unlike the car, it had no "monocoque" or unibody structure but a conventional ladder type chassis. It was a very conventional utility truck with an all-metal cabin for the driver and passenger, single window (the Bus and other variants had split windows), and a powertrain whic in option could be either the 1,911 cc (116.6 cu in) petrol I4 or the 1,767 cc (107.8 cu in) Diesel I4. The latter was the preferred choice for the Army for extra range.
The U23 had a wheelbase	of 3,380 mm (130 in) in 1935–40. Postwar, it was extended to 3,750 mm (150 in) in 1940–69, including with the 1958 facelift. Its length	also went from 5,080 mm (200 in) from 1935-1940 to 5,580 mm (220 in) in 1940–69. The width remained unchanged at 1,960 mm (80 in).
Modifications
The Type 23L series U was received at the Mines service on April 29, 1940. It had an extended chassis by 37 cm in wheelbase (1.2 ft) and its full loaded wieght was now 3,800 kg (8,377 Ibs). Its longer dropsides were made of pressed steel panels and no longer wood, the bed was now supported by five cross members instead of four. Upon their arrival in Paris in June, the Nazis took possession of the Citroën factory in Javel, and continued production of the Type 23L.
In September 1941, the T23L became the T23R with hydraulic brakes and a reinforced chassis, increasing the gross vehicle weight to 3,950 kg. In February 1945, the gross vehicle weight increased to 4,200 kg, and by the end of June 1952, to 4,500 kg. This latter version had curved front fenders, different from pre-war models, which extended down to the front bumper from November 1952. These fenders were further modified, closer to the wheels, with reinforcements in their rear section between May and October 1953.
Variants
23 L: Camionnette Non Spécialisée (general purpose lorry) 1800 kg, 4×2.
23 R: Camionnette Non Spécialisée (general purpose lorry) 2 tonne, 4×2
23 U: Camionnette Non Spécialisée (general purpose lorry) 1.5 tonne, 4×2
23 Body "Benne Entrepreneur" (Dump truck), "Plateforme Basculante" (Tilting Platform)
23 Body "Marchande" (Commercial), pickup flatbed, not tilting.
23 Car, 16-17 Places (16-17 Seat Bus).
The Citröen U23 in service
U23 of the FFI
The French vehicles were generally used in all units of the French frontline military, notably freshly reorganized DLM (Division Legere Mecanisee), DCs (Division Cuirassées), Cavalry units, artillery units, and specific organic batteries. One examplej the "Batterie Antichar Automotrice" or BAA (antitank self propelled battery) comprised a section of self-propelled 47mm guns of five 
Laffly S15 TCC a Laffly V15R staff car, three Citroen P54 supply half track, two recce motorcycle for the section, then an AA section comprising four Laffly W15T towing 25mm DCA guns, a staff vehicle Peugeot 402, a single supply 3.5t heavy Citroën U45 truck, two U23 repair and supply trucks, and two more in the support section led by a Laffly S 14F ARV. 
Since the French army was short of self-propelled vehicles of all sorts for specific used, it became common to create ad hoc sections with Citroën U45s mounting a mortar, a 25 mm APX AT gun or a 13.2 mm single or twin heavy machine gun mount for AA support. The Citröen U23 was appreciated by the crew, as a modern and rugged enough vehicle, but it obviously lacked off-road capabilities and was found bogged down during the "phoney war"'s autumn 1939 and winter 1939-1940. On road they were fasy=t, reliable, had a reliable range. Citroën proposed to fit blakout lights but the serie stopped apribtly with the armistice in June 1940. Many had fittings also to strap shovels.
Citröen famously worked for the Germans during the war, unwillingly. Founder André Citröen died in 1935 so the company was led by Pierre-Jules Boulanger. Citroen produced 32,248 vehicles for the Germans and 2,052 for French clients, to be precised between 1941 and 1944 some 7,700 Type 23 trucks (seen here), 6,000 Type 32U trucks and 15,300 Type 45 trucks. But the level of sabotage was elevated to an art form. One common practice was marking dipsticks low. Engines dried and seized in action on the eastern front. Many ideas from resistance leader and Ettore Bugatti’s right-hand man parachuted to France and British secret agent. 
In german service, the U23 became known as the Citroen type 23 U/LU (1.5/1.8 tons payload) which existed in two wheelbases (4,000 produced). The Germans only asked to add the Notek headlights they provided. Many vehicles also received improvized utility cabs, improvised box bodies depending on the use. The next model was the type 23 RU, which payload was increased to 2 tons, for an additional 3,700 made from 1941 to 1944. Despite the sabotages and their poor off-road performances, they were liked by the German crews and participated to the massive supply train of the three army groups deployed in Russia and Ukraine until 1944.
Back in France in 1958, the U23 underwent a major restyling to sport its typical wide horizontal grille incorporating headlamps, previously mounted to the fenders. The U23 like the traction Avant remained popular until gradually replaced by the Citroën 350 to 850 ("Belphégor") from 1964 onwards. Amazingly, Citröen maintained production of the U23 until 1969. The model was very popular with enthusiasts of the brand and like the Traction Avant, many are still running today.
| Specs Citröen U23 | 
| Dimensions : | 5,080 mm (200 in) x 1,960 mm (80 in) x 2,760 mm () | 
| Total weight: | 2,020 kg | 
| Useful load: | 1,500 kg | 
| Crew: | 2+8 | 
| Propulsion: | 1,767 cc (107.8 cu in) Diesel I4 45 hp | 
| Geabox: | Manual 4+1 | 
| Speed: | 70 km/h | 
| Range: | c500 km | 
| Production | 13,000 (+7,700 German) | 
Links/Src
citroenet.org.uk
ww2vehicles.co.uk
citroenorigins.co.uk
In german sevrice
history-making.com
lescolverts.forumactif.org
en.wikipedia.org
scalemates.com