Complex sentence: Tomsky moved to Estonia (then part of the Russian Empire) and was involved in the 1905 Revolution and helped form the "Revel Soviet of Workers' Deputies" and the "Revel Union of Metal Workers".
Split into simpler sentences: Tomsky moved to Estonia (then part of the Russian Empire) and was involved in the 1905 Revolution. He helped form the "Revel Soviet of Workers' Deputies" and the "Revel Union of Metal Workers".