Complex sentence: In 1917, Isakov moved to Petrograd, Russia, and entered the Naval Guards School of the Imperial Russian Navy and graduated as a midshipman in March of that year and briefly saw action against the Germans in West Estonian archipelago (Moonsund archipelago).
Split into simpler sentences: In 1917, Isakov moved to Petrograd and entered the Naval Guards School of the Imperial Russian Navy and graduated as a midshipman in March of that year. He briefly saw action against the Germans in West Estonian archipelago (Moonsund archipelago).