The 1st Tank Regiment was created on 1 August 1919 and the 2nd Tank Regiment on 1 November 1939. On 17 April 1941 they were united to form the 1st Armored Division. The old tanks from 1919 were assigned to a training unit (the FT Tank Battalion).

The 1st Regiment was equipped with 126 R-2s (Skoda LT VZ 35) and the 2nd Regiment with 75 R-35s (Renault R 35). The FT Tank Battalion had 75 FTs (Renault FT 17). All the tanks had 37 mm guns, but only the one of the R-2 was an efficient AT weapon. The others could only be used as anti-infantry guns. Also, the R-2 was faster and had a radio and was thus was more suited for blitzkrieg tactics and operations.

The 1st Armored Division was made up from the 1st and 2nd Tank Regiments, the 3rd and 4th Motorized Vanatori Regiments, the 1st Motorized Artillery Regiment, the Special Weapons Battalion, the Motorized Recon Group, the Communications Company, the Motorized Pioneer Battalion, the Service Group, the Traffic Platoon and the Police Platoon. It was organized with the help of German instructors from the 64th Panzergrenadier Regiment, the 4th Panzer Regiment and the 4th Flak Regiment.

Because of the big difference between the two tank types, the 2nd Tank Regiment was assigned to the 4th Army, which used it in the battle in southern Bessarabia and at Odessa. Thus, in the 1941 campaign, the 1st Armored Division had only the 1st Tank Regiment under its command.

A regiment was made up of two tank battalions, each battalion from 3 tank companies and one maintenance company. The difference between the two regiments was the number of platoons per each company. The 1st Tank Regiment had 5 platoons per company (of 3 tanks each) and the 2nd Tank Regiment had 3 platoons per company. Each regiment had 4 47 mm Schneider model 1936 AT guns and 2 13.2 mm Hotchkiss model 1939 AA machine-guns. At battalion level there were another 4 AA machine-guns.

During the 1941 campaign, the 1st Division was used according to the German military doctrine as a shock unit and it was very successful in the battles in Bessarabia and in the encircling operation at Odessa. It was assigned to the 4th Army and took part in the actual assault on Odessa. The tanks were deployed in small formations and, because of the lack of cooperation between the infantry and the tanks, the 1st Armored Division suffered heavy losses in men and equipment. At the end of September 1941, from the division's remains was created the "Lt.Col. Eftimiu" Mechanized Detachment. It was made up of a tank battalion (20 R-2s), a motorized vanatori battalion, a 105 mm Schneider model 1936 field guns battalion, a 100 mm Skoda howitzers battalion, a pioneer company, a 20 mm Gustloff model 1938 AA guns company, a 37 mm Rheinmetall model 1939 AA guns battery and an AT company (12 47 mm Schneider model 1936 AT guns). After Odessa was captured, the detachment was disbanded. During the first campaign, the 1st Armored Division lost: 34 officers, 102 NCOs, 1,125 soldiers, 463 rifles, 54 LMGs, 5 HMGs, 206 vehicles and 111 tanks.

The division was reorganized and in the autumn of 1942 was sent to the front, near Stalingrad, where it was subordinated to the 48th Panzer Corps. The 1st Tank Regiment was again active. It received 11 T-3s (Pz IIINs) and 11 T-4s (Pz IVGs). The AT artillery was strengthened with 9 75 mm Pak 40s and 9 50 mm Pak 38s. The guns were towed by Zugkraftwagen tractors. The Motorized Recon Group received Sdkfz 222s.

Before the battle of Stalingrad, the 1st Armored Division consisted of the 1st Tank Regiment, the 3rd and 4th Motorized Vanatori Regiments, the 1st Motorized Artillery Regiment, the Motorized Special Weapons Group, the Motorized Recon Group, the Motorized Pioneer Battalion, the AT Battalion, the AA Company, the Communications Company, the Service Group, the Traffic Platoon and the Police Company. It had 501 officers, 538 NCOs, 11,592 soldiers, 9,335 rifles, 278 LMGs, 61 HMGs, 67 mortars, 36 guns and howitzers, 1,358 vehicles, 109 R-2 tanks, 11 T-3 tanks, 11 T-4 tanks, 2 captured Soviet tanks, 10 AB armored cars (Sdkfz 222) and 8 TB armored personnel carriers (SPW 251).

The 1st Tank Regiment was made up of two battalions, each having four companies: 3 companies of R-2s and one medium tank company (the T-4s were assigned to the 4th Company/1st Battalion and the T-3s to the 8th Company/2nd Battalion). The medium tank companies proved to be the only ones capable of resisting more efficiently to the heavier Soviet tanks. However, during the Stalingrad campaign the 1st Armored Division suffered heavy losses: 130 officers, 87 NCOs, 3,067 soldiers, 3,000 frostbites, 474 rifles, 149 LMGs, 22 HMGs, 55 mortars, 22 guns, 678 vehicles and 86 tanks.

In March 1943 a tank battalion, equipped with 50 T-38s (CKD LT VZ 38s), was sent on the front to reinforce the Cavalry Corps and the Mountain Corps in the Kuban. It had 3 companies (51st, 52nd and 53rd) each 15 tanks strong. Five tanks were kept in reserve for replacements. After the retreat from the Taman bridgehead, the battalion was used in the fights in Crimea in late 1943. It returned to Romania in early in 1944, with only 10 tanks still operational.

In the same period was formed the Rapid Detachment from some elements of 1st Armored Division, with purpose of offering better training conditions. It consisted of a self-propelled gun company (12 TACAM T-60s), a AT and AA company, a motorized artillery battalion and one Sdkfz 222 (used as a communications vehicle). The Detachment was disbanded in October 1943.

On 28 October 1943 the "Law for the organization of the Armed Forces" was promulgated. Through it were created the Mechanized Troops Command, the 1st Armored-training Division and the 8th Motorized Pioneer Regiment. Tanks, assault guns and armored cars were ordered from Germany and, in the same time, several attempts to build armored fighting vehicles were made in Romania.

On 24 February 1944, because of necessity to stop the advance of the Red Army that had entered on Romanian soil and because the 1st Armored Division wasn't operational yet, the "Cantemir" Mixed Armored Group was organized and rushed to the front. It was made up of two tank companies (30 T-4s and 2 T-3s), one assault gun company (10 TAs, the Romanian designation for the StuG IIIG), two batteries of Romanian-built self-propelled guns (14 TACAM T-60s), one R-2 tank company and one R-35 tank company. The group operated on the front until April 1944.

On 28 March 1944, the Rapid Armored Detachment was created from elements of the 1st Armored Division. It consisted of the Motorized Recon Group, the Motorized AT battalion (6 75 mm Resita model 1943 AT guns), the 63rd TACAM T-60 Battery, the Tank Battalion (2 tank companies each equipped with 16 T-4s and one self-propelled gun company equipped with 12 TAs), the Motorized Vanatori Battalion (two rifle companies and one 120 mm mortar platoon), the Motorized Artillery Battalion (12 100 mm Skoda howitzers), the AA Company, the Ambulance and service units.

The Rapid Detachment was sent on the front in Moldavia in Moldavia and constituted the nucleus around which was rebuilt the 1st Armored Division "Greater Romania" (it received this name on 28 April 1944). The latter unit's order of battle is listed below:

• 1st Tank Regiment: 1st Tank Battalion (3 companies), 2nd Assault Gun Battalion (3 companies), command platoon
• 3rd and 4th Motorized Vanatori Regiments
• 1st Motorized Artillery Regiment
• Special Weapons Motorized Group: Motorized Recon Group, Motorized Pioneers Battalion
• AT Artillery Battalion
• AA Company

The division was used by the Romanian command to stop and then , following the failure of this mission, to delay the Soviet advance in the Iasi area between 19 and 23 August 1944, suffering substantial losses in the process. After the fighting with the Red Army had ceased, the 1st Armored Division was captured by the Soviets. A part of its troops were interned in POW camps, while the other part was used to organize the "Lt. Col. Gh. Matei" Armored Detachment (the deputy commander of the 1st Tank Regiment). It was made up of a tank company (9 T-4s), an assault gun company (7 TAs), a motorized vanatori battalion, a pioneer company, an AA company (25 mmm Hotchkiss model 1939 AA guns), the 101st AT Company (12 75 mm Resita model 1943 AT guns). In total it had 133 vehicles and 1,058 soldiers. The Detachment crossed the mountains to Transylvania and fought under Soviet command, supporting the 24th Guards Corps, until 28 September when it returned to Romanian command.

On 24 August 1944, the Mechanized Training Center at Targoviste organized the "Gen. Niculescu" Armored Detachment (aka "Jupiter" Armored Detachment ). It was formed from a recon group, a tank battalion (one company equipped with 10 T-4s and one company equipped with 10 TAs), one TACAM battalion (12 TACAM R-2s), a motorized vanatori battalion from the 4th Motorized Vanatori Regiment, and an AT company (12 75 mm Resita model 1943 AT guns). It took part in the fights in Bucharest, Baneasa, Otopeni and then in Transylvania as part of the Mechanized Corps. It was disbanded on 28 September.

With the troops of the 1st Armored-training Division was organized the "Mr. Victor Popescu" Armored Detachment. It had one R-2 tank company, one T-38 tank platoon, one R-35 tank platoon, motorized vanatori units, AA and AT units. It fought around Ploesti and was disbanded on 31 August.

On 1 October 1944, from the elements of the "Lt. Col. Matei" and "Gen. Niculescu" detachments was formed the 4th Army's Armored Group. It consisted of a recon company (5 AB armored cars, one SPW 250, a section of amphibious VW and Horch cars), one tank battalion (a company with 10 T-4s, a company with 8 TAs and a company with 16 TACAM R-2s), the 62nd TACAM T-60 Battery, a motorized vanatori battalion, an AT company (12 75 mm Resita model 1943 AT guns), a motorized heavy artillery battalion, a pioneer company, an AA company (25 mm Hotchkiss model 1939 AA guns), a communications platoon and a service company. It was used in the fights in northwestern Transylvania and in Hungary until the beginning of November 1944, when it was disbanded.

According to the armistice protocol, the 1st Armored Division, the 1st Armored-training Division, the Mechanized Training Center and all their subordinated units were disbanded. Only the 2nd Tank Regiment remained. It was sent to the front in Slovakia in February 1945 and from March 1945 was assigned to the Soviet 27th Guards Tank Corps. The regiment was made up of the:

• Recon Company: 8 ABs and 5 TBs
• 1st Tank Battalion: one tank company (8 T-4s) and 2 assault gun companies (13 TAs)
• 2nd Light Tank Battalion: 2 R-35 tank companies (28 R-35s and R-35/45s), one T-38 tank company (9 T-38s) and one TACAM battery (5 TACAM R-2)
• Recon Tank Group: 2 R-2s
• AA Battery: 4 20 mm Gustloff model 1938 AA guns
• Command Company: radio communications platoon, cable communications platoon and a pioneer platoon.