The first regular military formation of the Whites was the Special Manchurian Detachment (SMD) made up of 9 officers, 35 Cossacks and 40 Buryats on December 12, 1917, by Grigory Semyonov. By August, 1918 the SMD had a considerable force and its strength grew because of the Japanese military assistance. The Japanese were interested in gaining Transbaikal and its resources and especially they supported Grigory Semyonov as a result of confrontation with British-supported Admiral Kolchak.
The Special Manchurian Detachment and the Japanese Expeditionary Corps launched the first massive offensive in order to conquer Chita in the spring of 1918 but were repelled. Finally, Chita was taken on 25 August 1918. It was the beginning of the Siberian Intervention of the Japanese and Chita became the headquarters of the Japanese 5th Division for more than two years.
The first action of the newly formed White government was to “encourage” Baikal Cossacks to join the White Army of Grigory Semyonov. Baikal Cossacks were drafted in the newly formed military formations among them even the Jewish regiment was created in order to raise all possible resources. All in all, Ataman Semyonov managed to make up 20,000 strong army as of May 1920.
After taking Chita and expelling the Soviets in the summer of 1918, the future Ataman Semyonov and his advisers started forming new governmental institutions. On August 25, 1918, the Provisional Oblast Government was initiated in Chita by the former members of the Chita Town Duma, the Transbaikalian Oblast Zemstvo, and the Chita Uezd Board. The Provisional Oblast Government included many Jews of various political affiliations.
The Government announced itself under jurisdiction of the Provisional Siberian Government located in Omsk and immediately annulled all Soviet acts related to confiscations.
On September 14, 1918, Grigory Semyonov arrived at Chita and together with the Japanese he started his rising to autocracy. He became the Commander-in-Chief of the Separate Eastern Siberian Army, pronounced the Ataman of the Baikal Cossacks, and finally on July 9, 1919, Admiral Kolchak’s Government appointed him as the Head of all Governmental Institutions of Transbaikal.
Although he became an autocratic ruler of Transbaikalia, Ataman Semyonov kept all representative bodies such as Oblast and Uezd Assemblies and Boards, Town Dumas, and trade unions. In addition, Ataman Semyonov let political activities of various parties even the Bolsheviks if they didn’t attempt to break current laws.
From the first months of his rule over Transbaikal, Grigory Semyonov had chosen terror as an oppressive means against the displeased. It didn’t bring expected results but the start of the massive resistance partisan movement. Ataman Semyonov tried to be more liberal to different social strata but it was impossible to pacify all conflicting groups.
Together with the Japanese he launched a series of military operations against the partisan resistance movements of Baikal Cossacks and local peasants. One of the notable operations against the partisans was the Battle of Bogdat in the autumn of 1919 in which Grigory Semyonov was close to put an end to the Eastern Transbaikalian Front. The actions of the Japanese and Semyonov’s troops were brutal to the partisans and locals. As a result, many locals joined the partisans and they became a considerable force of about 30,000 of the Amur Front. The latter had played a significant role of putting the end to Ataman Semyonov’s regime in Transbaikal in the autumn of 1920.