After Russia's conquest of Finland in 1809, the estates in Finland swore an oath to the Emperor in the Diet of Porvoo. A Finnish House of Nobility was codified in 1818 in accordance with the old Swedish law of 1723. However, after the Diet of Porvoo, the Diet of Finland was reconvened only in 1863. In the meantime, for a period of 54 years, the country was governed only administratively.