Battle for the DonbasDonbas, Ukraine
After the army of the Ukrainian People's Republic was pushed out of Kharkiv and Kyiv and the Ukrainian Socialist Soviet Republic was established, in March 1919 the Red Army attacked the central part of Donbas, which had been abandoned by the Imperial German Army in November 1918 and subsequently occupied by the White Volunteer Army. Its aim was to control strategically located and economically important territories, which would enable a further advance towards Crimea, the Sea of Azov and the Black Sea. After heavy fights, fought with variable luck, it took over key centers in this area (Yuzivka, Luhansk, Debaltseve, Mariupol) until the end of March, when it lost them to the Whites led by Vladimir May-Mayevsky.
On April 20, the front stretched along the Dmitrovsk-Horlivka line, and the Whites actually had an open road towards Kharkiv, the capital of the Ukrainian SSR. Until 4 May, their attacks were resisted by Luhansk. Further successes of the Armed Forces of South Russia in May 1919 were favored by the conflict of the Reds with the anarchists of Nestor Makhno (who were still their allies in March) and the rebellion of the Bolshevik ally, Otaman Nykyfor Hryhoriv.
The Battle for Donbas ended at the beginning of June 1919 with a complete victory for the Whites, who continued their offensive towards Kharkiv, Katerynoslav, and then Crimea, Mykolaiv and Odesa.