They were wed when she was 16 but arranged marriage was never happy and Peter aged 18 showed no interest in his young bride.
Before he was admitted into Catherine's personal apartments the young man would be examined by a physician to be sure of health and if he passed both tests, would be installed as her lover until she tired of him.
Prince was the last of her favourites and the most powerful man in the Russian Empire during the last years of her reign.
Conspiracy speculation had her die at the hands of assassins who cunningly placed spring blades hidden in a toilet seat.