1801 - Paul I dies and the Russian crown falls to his eldest son who becomes Alexander I.
1820 - Alexander is approached by his brother, Constantine, who wishes to marry Joanna Grudzinska, Princess of Lowicz. The marriage will be morganatic and Alexander says he will only recognise it should Constantine forfeit his rights to the throne - which Constantine accepts and subsequently marries Joanna.
1825 - Despite Constantines previous (secret) forfeit of the throne in order for him to marry Joanna, Grand Duke Nicholas (Constantines younger brother) refuses to ascend to the throne until Constantine confirms his refusal - this leads to an Interregnum which lasts until Constantine, Viceroy of Poland, arrives back in St Petersburg and accepts the throne.
1831 - Constantine dies (much to the relief of the Polish and the Russians who largely considered him a tyrant), leaving his son, ten year old Pavel Constantinovich, to become Tsar under the Regency of his uncle, Grand Duke Nicholas.
1839 - Paul II reaches majority and helps arrange the marriage between his cousin, the Grand Duke Alexander Nikolaevich and Princess Alexandrina Victoria of Kent and Strathearn.