Complex sentence: In the aftermath, the Finns passed from Russian rule to the German Empire's sphere of power, including the conservative Finnish Senate's attempt to establish a Finnish monarchy, but after the defeat of Germany in WWI, Finland emerged as an independent, democratic republic.
Split into simpler sentences: In the aftermath, the Finns passed from Russian rule to the German Empire's sphere of power. The conservative Finnish Senate's attempted to establish a Finnish monarchy, but the plan was aborted by the defeat of Germany in World War I. Finland emerged as an independent, democratic republic.