On 12 January, the Tsar appointed Dmitri Feodorovich Trepov as governor in St Petersburg and dismissed the Minister of the Interior, Pyotr Sviatopolk-Mirskii, on 18 February  1905. He appointed a government commission "to enquire without delay into the causes of discontent among the workers in the city of St Petersburg and its suburbs" in view of the strike movement. The commission was headed by Senator NV Shidlovsky, a member of the State Council, and included officials, chiefs of government factories, and private factory owners. It was also meant to have included workers' delegates elected according to a two-stage system. Elections of the workers delegates were, however, blocked by the socialists who wanted to divert the workers from the elections to the armed struggle. On 5 March  1905, the Commission was dissolved without having started work. Following the assassination of his uncle, the Grand Duke Sergei Aleksandrovich, on 17 February  1905, the Tsar made new concessions. On 18 February  1905 he published the Bulygin Rescript, which promised the formation of a consultative assembly, religious tolerance, freedom of speech  and a reduction in the peasants' redemption payments. On 24 and 25 May  1905, about 300 Zemstvo and municipal representatives held three meetings in Moscow, which passed a resolution, asking for popular representation at the national level. On 6 June  1905, Nicholas II had received a Zemstvo deputation. Responding to speeches by Prince Sergei Trubetskoi and Mr Fyodrov, the Tsar confirmed his promise to convene an assembly of people's representatives.. The Tsar appointed Dmitri Feodorovich Trepov as governor in St. Petersburg on what date?