Peter the Great died on the 8th of February 1725. He was 52 years old, had reigned for forty of those years and transformed Russia from a struggling, landlocked state to a major and still expanding empire. But he died without appointing an heir.

At the start of week 3 of BBC Radio 4's major new History series, Russia - The Wild East, Martin Sixsmith traces the power struggles after the death of Peter, until another Great leader emerges. While Peter the Great had laid the foundations of Russia as a European power, it was under Catherine the Great that Russia became Europe's most feared superpower.

One of the reputations that Catherine acquired was of a woman with a healthy interest in sex, but this shouldn't overshadow her reforming zeal. She modernised the legal system, took ideas from the great Enlightenment thinkers Diderot and Voltaire, and learnt by heart long passages from Montesquieu's iconic manifesto of constitutionalism, on the separation of powers, civil liberties and the rule of law.

"It seemed to many," Martin Sixsmith suggests, "that Russia was preparing to boldly go where few others would dare to tread - having been the most backward of the European powers, she now appeared to be leading the way to the enlightened future."

But an ingrained fear of vulnerability lay beneath this show of strength, and Catherine followed an aggressive programme of expansion especially to the south. It provided a buffer against enemies on her borders, but sowed the seeds of ethnic tensions that still exist today, and a careful observer would have realised even at this stage that Catherine was setting very clear limits to the extent and nature of the changes she was prepared to allow.

Historical Consultant: Professor Geoffrey Hosking

Producers: Adam Fowler & Anna Scott-Brown
A Ladbroke Production for BBC Radio 4. Show less