The 'Voronezh-Voroshilovgrad Strategic Defensive Operation' was centred on the Battle of Voronezh, otherwise the 1^st Battle of Voronezh, and was a Soviet offensive fought in and around the strategically important city of Voronezh on the Don river, some 280 miles (450 km) to the south of Moscow as the Soviet forces' attempted response to the first stage of the German summer offensive (28 June/24 July 1942).

The Soviets divided the operation into four sub-operations as the '1^st Kastornoye Defensive Operation' (28 June/10 July), the '2^nd Kastornoye Defensive Operation' (9/24 July), the 'Valuiki-Rossosh Defensive Operation' (28 June/24 July) and the 'Voroshilovgrad-Shakhty Defensive Operation' (7/24 July).

The German attack known as 'Fridericus I' had two objectives. One was to sow in Soviet minds a high degree of confusion about the ultimate goals of the 'Blau' campaign. There was widespread feeling by almost all observers, and especially the Soviet high command, that the Germans would resume their attack on Moscow during the summer of 1942, and a strong offensive toward Voronezh, near the site of the Germans' deepest penetration of the previous year, might be successful in hiding the huge size of the 'decisive' campaign taking place farther to the south. Soviet forces sent to the area to bolster its defence could not move with the same speed as the German forces, who would then turn south and leave the Soviets in their wake. The other purpose was to provide an easily defended front along the Don river, providing 'Blau' with a strong left flank that could be protected with relatively light forces.

The plan involved forces of Generalfeldmarschall Fedor von Bock’s Heeresgruppe 'Süd', at this time in the far north of the army group’s primary area of responsibility. The attack was to be spearheaded by Generaloberst Hermann Hoth’s 4^th Panzerarmee, whose highly mobile forces were to sweep rapidly to the east in the direction of Voronezh and then turn to turn to the south-east to follow the Don river to Stalingrad. As the 4^th Panzerarmee moved out of Voronezh, the slower infantry forces of Generaloberst Maximilian Reichsfreiherr von Weichs’s 2^nd Army following behind them would take up defensive positions along the river. The plan called for the 2^nd Army to arrive just as the 4^th Panzerarmee was completing the clearance of the city, and Hoth was under orders to avoid any urban fighting that might bog down his army’s progress.

The city was defended by the troops of General Leytenant Mikhail A. Parsegov’s 40^th Army as part of the 'Valuiki-Rossosh Defensive Operation' of General Letenant Nikolai F. Vatutin’s South-West Front.

Hoth’s powerful armoured formation moved forward with little delay in the first days of 'Fridericus I', and the only natural barrier before the city was the Devitsa river, an arm of the Don running through Semiluki just a short distance to the west. For reasons that remain unclear, the bridge over the Devitsa river was not destroyed, and Hoth’s formation was able to sweep aside the defensive forces placed there and penetrate to the outskirts of Voronezh on 7 July. Soviet forces then mounted a successful counterattack that pinned Hoth’s forces.

It was at this time that the 4^th Panzerarmee was to have been relieved by the infantry forces, but these latter were still far from the city. Intense house-to-house fighting broke out, and Hoth continued to push forward while he waited. At one point Generalmajor Helmuth Schlömer 3^rd Division (mot.) broke across the Don river but then pulled back. The Soviet high command poured reserves into the city, and there developed a situation smaller but not dissimilar to that which was to eventuate at Stalingrad a few months later, with the German troops clearing the city street by street with flamethrowers while tanks gave fire support.

The 2^nd Army did not arrive for another two days, by which time the 4^th Panzerarmee was heavily engaged and therefore needed some time to remove itself from the line. The 2^nd Army continued the battle until 24 July, when the last Soviet forces to the west of the Don river were defeated and the fighting ended. Adolf Hitler later came to believe that these two days, when combined with other avoidable delays in the drive to the south, allowed Marshal Sovetskogo Soyuza Semyon K. Timoshenko to reinforce the forces in Stalingrad before the 4^th Panzerarmee could arrive and become key to the planned swift seizure of Stalingrad.

The Soviet forces recaptured the city in the Battle of Voronezh of 1943.