In parallel with the conversion of captured tanks, research started in December 1942 for development of a Romanian tank-destroyer. The solution of Marshal Ion Antonescu was the construction of a light, highly mobile and powerful armed vehicle that Romanian industry could handle alone. The research team made of Major Nicolae Anghel and Captain Gheorghe Sambotin had to develop an unique vehicle having at its disposal components of local or captured material. With the help of engineer Constantin Ghiulai, they started by mounting the 122mm Putilov-Obuhov howitzer model 1904/30 and a coaxial 7.92mm ZB machine-gun on a modified T-60 chassis. The upper structure was made of four sloped armour plates 20-30mm thick that was giving vehicle a turtle shape. The resulting prototype, nicknamed Maresal (marshal), has received designation M-00 and the preliminary trials that took place on 30 July 1943 at Suditi revealed underpower and problems related to the gun carriage. Experiments continued and by October 1943 three more prototypes (M-01, M-02 and M-03) were completed at Rogifer Works, all similar in aspect with the first prototype but having a more powerful engine of 120hp and reinforced armour. The M-03 had a larger chassis, welded armour plates and a reinforced inner structure. The vehicle had a crew of two, the driver which was also taking the aim sitting in the right part of the compartment shoulder to shoulder with the loader. The shells used for the 122mm gun were hollow-charge Hohllandung. On 23 October 1943 the three prototypes were tested at Suditi in the same time with the trials of the exceptional 75mm DT-UDR No.26 anti-tank gun. The proposal made by Colonel Paul Draghiescu, one of the designers of Maresal, of mounting the Romanian anti-tank gun instead of the Soviet gun was immediately approved and would be included in the M-04 prototype.

In November 1943 the preparation for mass production started. 1000 Hotchkiss engines were ordered from France while other components still not made in Romania were requested from Germany. The new vehicle immediately attracted the German attention and in December 1943 Antonescu presented to Hitler the project and the blueprints of M-04 prototype. Those inspired the German development of the Hetzer tank-destroyer that assumed the mounting of a 75mm gun on the Czech LT vz.38 tank's chassis.

The work at the M-04 prototype started in November 1943 and lasted until January 1944. The new prototype had Hotchkiss H-39 engine and 75mm DT-UDR anti-tank gun. In February it was tested at Suditi and its performance impressed the OKH officials which were attending trials. Hitler personally offered to support the project by dispatching specialists and materials to Romania. During March-May 1944 the development team which now was including Alkett and Vomag specialists worked at the M-05 and M-06 prototypes which comprised mostly Romanian components. The only foreign components were the Hotchkiss engine, the gearbox, the CKD tracks, the Telefunken radio and part of the optics. In June 1944 the M-05 contested a Sturmgeschutz III in the attendance of Marshal Antonescu and in several tests of mobility and firepower was superior.

On 10 May 1944 the High Command of Mechanisation ordered the production of 1000 Maresal tank-destroyers that would have formed thirty-two anti-tank battalions. A training battalion (designated M Battalion) was formed in the 2nd Tank Regiment. The first series of 10 vehicles was planned for June and it was estimated a production of 100 pieces per month by September. Due to the allied bombings that disrupted the communication lines, the delivery of first series was postponed for 1 November 1944. It has been decided that the first 200 Maresal tank-destroyers to be M-05 and the rest of 800 to be M-06. On 8 June 1944 a convention was signed by the Romanian Ministry of Defence and OKH, which foresaw the co-operation for the mass production of Maresal/Hetzer and a German order for several dozens of Maresal. Germans also offered the license of Praha engine used by the Hetzer and even the complete license of Hetzer.

Between 24 July and 21 August the M-05 was the subject of a very hard endurance test ended with the detaching of the gun carriage. The events following 23 August 1944 led to the cancellation of production on 29 August. However, it has been decided the resuming of trials with the M-05 and the finishing of the first series of ten vehicles. Invoking the terms of armistice, on 26 October the Soviets confiscated the prototypes, the first series that was almost completed and everything related to the Maresal.

Specifications

M-05 Prototype
Crew	2
Weight	10t
Dimensions
Length	5.8m
Width	2.44m
Height	1.54m
Engine
Type	Hotchkiss H-39
Power	120hp
Fuel	petrol
Performance
Max road speed	45km/h
Max cross-country speed	25km/h
Armament
Main	1 x 75mm DT-UDR gun
Secondary	1 x 7.92mm ZB-53 mg
Armour
Armour	10-20mm