15th Tank Corps

The 15th Tank Corps (Russian: 15-й танковый корпус, 15-y tankoviy korpus) was a tank corps of the Soviet Union's Red Army. It formed in 1938 from a mechanized corps and fought in the Soviet invasion of Poland, during which it participated in the capture of the Grodno and Augustów Forest from Poland. The corps was disbanded in January 1940 at Vilnius and Šalčininkai in Lithuania.

In 1942, the corps was reformed under the command of Major General Vasily Koptsov and became part of the 3rd Tank Army. It first saw combat in the unsuccessful Kozelsk Offensive of late August and early September, a relatively small operation to encircle a German salient, which resulted in the corps taking heavy losses in proportion to the territory gained. After spending the rest of the year in reserve, receiving new supplies and equipment, the corps was transferred to the southern front in southwestern Russia to fight in the Ostrogozhsk–Rossosh Offensive during January 1943, in which it played a major role by forming part of the forces that encircled thousands of Axis troops on the middle reaches of the Don River.

In February 1943, the unit fought in Operation Star, achieving its objective of recapturing the key city of Kharkov in eastern Ukraine. As the Soviet advance outran its supply lines, the corps was slowly worn down and was virtually destroyed after being surrounded by a German counteroffensive in the Third Battle of Kharkov during late February and early March. Koptsov was among those killed in the fighting. The corps was rebuilt in the following months and became part of the newly created 3rd Guards Tank Army, fighting in Operation Kutuzov, the Soviet counteroffensive during the Battle of Kursk, in late July. For its actions in the offensive, the corps was converted into the 7th Guards Tank Corps.

The 15th Tank Corps formed in 1938 from the 5th Mechanized Corps at Naro-Fominsk in the Moscow Military District, inheriting the honorific "named for (Konstantin) Kalinovsky", a Soviet military theorist. Commanded by Komdiv (equivalent to Lieutenant General) Mikhail Petrovich Petrov, the corps included the 2nd Light Tank Brigade (previously the 5th Mechanized Brigade), the 27th Light Tank Brigade (formerly 10th Mechanized Brigade), the 20th Motor Rifle and Machine Gun Brigade (formerly 50th Rifle and Machine Gun Brigade), and the 401st Separate Communications Battalion, a support unit. Soon after its formation, the corps was transferred to the Belorussian Special Military District, its headquarters located in Borisov. The 2nd and 27th Light Tank Brigades were based in Borisov, and the 20th Motor Rifle and Machine Gun Brigade was based in Mogilev. The 89th Separate Air Liaison Flight formed as part of the corps at Borisov on 4 August, operating Polikarpov R-5 and U-2 biplanes.

The corps fought in the Soviet invasion of Poland in September 1939, as part of Ivan Boldin's Dzerzhinsky Cavalry-Mechanized Group (KMG). The invasion was conducted under the terms of the Molotov–Ribbentrop Pact, which divided Poland between the Soviet Union and Nazi Germany and guaranteed that neither country would attack the other. At the beginning of the campaign, the 2nd Brigade had 234 BT-7 light tanks and 30 BA armored cars, the 27th Brigade had 223 BT-7s and 31 BAs, and the 20th Brigade had 61 BAs; the corps thus fielded 461 tanks and 122 armored cars. On 17 September, at 05:00, the corps, advancing on the KMG's southern flank, crossed the state border, overran the Polish border guards, and began a rapid advance without resistance; most of the Polish troops in the east had been transferred west to fight against the German invasion of Poland earlier in the month. By 12:00, the 27th Brigade had reached Mir and Ajucavičy, overrunning the practically undefended Nowosiółki–Kajszówki sector of the Baranovichi Fortified Region. By the end of the day, the 27th Brigade had crossed the Servach River in the Lubanichi area, the 2nd Brigade had crossed the Usza River, and the 20th Brigade had advanced to the border at Losha. During the day, the corps suffered casualties of one killed and two wounded. On 18 September, the 27th Brigade advanced from the line of Rudašy and Zaberdowo, but was bogged down for several hours while moving through the area near Golewicze. As a result, it did not reach the Jarniewo area, 2 kilometers (1.2 mi) west of Slonim, until the morning of 19 September. After the retreating Polish garrison burned one of the two bridges over the Shchara River, the 2nd Brigade entered Slonim and disarmed 80 policemen. On 19 September, the brigade reached Vawkavysk, and the corps was ordered to take Grodno and Sokółka by the end of the day, in conjunction with the motorcycle units of the 4th and 13th Rifle Divisions. At the same time the 27th Brigade captured Dvorets, disarming 400 people and capturing 300 rifles, but fuel shortages kept the corps stretched out along the Slonim–Vawkavysk road awaiting refueling. The 20th Brigade approached Slonim from the east, further clogging the roads and delaying the arrival of supply units.

After receiving fuel from 07:00 on 20 September, the units of the corps began to advance on Grodno in multiple waves. At 13:00, 50 tanks from the 27th Brigade reached the southern outskirts of the city, beginning the Battle of Grodno. By 14:00, the 2nd Brigade had taken Sokółka, and its advance units had reached Dąbrowa. At the end of the day, motorcycle units of the 4th Rifle Division and battalions of the 20th Motor Rifle and Machine Gun Brigade, which had all been delayed by fuel shortages, had reached the city. Grodno was defended by an understrength force of up to 3,000 Polish officers, gendarmes, and volunteers who had burned the bridges across the Neman. The 27th Brigade's reconnaissance battalion launched the first attack with 12 tanks and an armored car, and was later joined by two tank battalions with a total of 36 tanks. By 19:00, two battalions of the 13th Rifle Division's 119th Rifle Regiment had arrived at Grodno, and on the morning of 21 September they were reinforced by two battalions of the 4th Rifle Division's 101st Rifle Regiment and the motorized detachment of the 16th Rifle Corps, the latter of which was subordinated to the corps for the duration of the battle. By the end of 20 September, the combined forces had captured the southern part of Grodno.

At 07:00 on 21 September, the artillery batteries of the two rifle regiments and the 20th Brigade commenced firing from the southern bank of the Niemen, demolishing the main Polish strongpoints—barracks, churches, and trenches—on the northern bank of the Niemen. The 119th Regiment then crossed to the north bank and rebuilt a bridge for the tanks to use. After defeating a group of Polish officers in the Poniemuń district, the regiment captured the eastern part of the city. Meanwhile, the 101st Regiment and a tank company from the 27th Brigade, which crossed the river behind the 119th, destroyed a group of about 250 officers defending the wooded hills 1.5 kilometers (0.93 mi) east of the city, then advanced northeast and captured the railway station by the end of the day. The 20th Brigade captured the southwestern part of the city, but was unable to advance northward because of strong Polish resistance in the houses and trenches near the bridge and the tobacco factory. The Soviet advances on 21 September resulted in the suppression of large pockets of resistance, and during the night, remnants of the Polish defenders retreated in the direction of Sapotskin and Suwałki.

Grodno was cleared of Polish troops on 22 September. The 27th Brigade lost two burned and 12 damaged BT-7 light tanks in the battle, some to Molotov cocktails thrown by the defenders from attics and trenches, and its casualties totaled 19 killed and 26 wounded. The 20th Brigade lost a BA-10 to Molotov cocktails, suffering casualties of 3 killed and 20 wounded. The 16th Rifle Corps' motorized detachment lost 25 killed, 110 wounded, and a burned tank. During the battle, the corps killed 320 officers, 20 non-commissioned officers, and 194 soldiers, many of whom were crushed by tanks in the eastern part of the city. Between 20 and 21 September, they had captured 38 Polish officers, 20 non-commissioned officers, and 1,477 enlisted men, as well as 514 rifles, 146 machine guns, a mortar, and an anti-aircraft gun.