forces, despite having initially been sent to obtain grain for Moscow. Together, Voroshilov and Stalin established the North Caucasus Military District in order to rally the defense of the city and centralise control over all Red forces in the region. The army that Voroshilov assembled eventually became the 10th Army of the Southern Front. Meanwhile, ataman Pyotr Krasnov convinced the Don krug to occupy the cities bordering the Don Republic, including Tsaritsyn, Kamyshin, Balashov, Povorino, Novokhopyorsk, Kalach, and Boguchar. First siege (July–September 1918) From May to July 1918, the Don Cossacks under the command of Pyotr Krasnov were able to mobilize 40,000 men, equal in size but better trained than the Red troops present in the region. By the end of July, the Cossacks had cut the railway line towards Tsaritsyn and the Volunteer Army had seized a number of towns en route to the city, completely surrounding the Red forces in Tsaritsyn. The Don Cossacks launched their first attack on Tsaritsyn in late August 1918, but this offensive was repulsed by mid-September. The Bolsheviks, in turn, organized a counter-offensive along the three railway lines leaving the city. Although initially successful, the counter-offensive was halted after two weeks, when the Whites received reinforcements from Voronezh. The possibility of an offensive against Voronezh would pose a greater threat to the Soviet government in Moscow than the potential collapse of Tsaritsyn. Second siege (September–October 1918) Towards the end of September, as part of a broader reorganization of the entire Red Army, coordinated by its commander-in-chief Jukums Vācietis and the military commissar Leon Trotsky, the Red forces in Tsaritsyn were officially renamed the 10th Army. It was still commanded by Voroshilov, but the Bolsheviks reorganized the entire Southern Front, putting at its head the former Tsarist general Pavel Sytin. At this same time, a second Cossack offensive began under the general command of Pyotr Krasnov, and with the participation of a group of 50,000 cavalry under the command of Konstantin Mamontov. By mid-October the city was almost completely surrounded and the only advantage the Reds had was in artillery, which allowed them to keep control over the city. A conflict immediately broke out in Tsaritsyn between Stalin and Voroshilov on the one hand, and Trotsky, Vācietis and Sytin on the other. Stalin interfered with matters beyond his competence and urged Voroshilov to ignore Sytin's orders. When on 29 September 1918 Sytin arrived in