Complex sentence: The Referendum of 1946 that led to the transition from a constitutional monarchy to a people's republic, which took place during the Soviet occupation of the country, was also technically illegal since the Tarnovo Constitution did not provide for a change in the type of government.
Split into simpler sentences: The Referendum of 1946 led to the transition from a constitutional monarchy to a people's republic. The referendum took place during the Soviet occupation of the country, was also technically illegal since the Tarnovo Constitution did not provide for a change in the type of government.