Complex sentence: All in all, Ataman Semyonov managed to make up 20,000 strong army as of May 1920 and together with the Japanese he launched a series of military operations against the partisan resistance movements of Baikal Cossacks and local peasants.
Split into simpler sentences: All in all, Ataman Semyonov managed to make up 20,000 strong army as of May 1920. Together with the Japanese he launched a series of military operations against the partisan resistance movements of Baikal Cossacks and local peasants.