The Republic was officially proclaimed on 21 July 1807, after the French troops had handed over the city on May 27. Prussia and the Kingdom of Saxony under Frederick Augustus I, also Duke of Warsaw, were appointed guarantee powers. Marshal François Joseph Lefebvre, commander of the Danzig siege, received the honorific title of "" from the hands of Napoleon, however, the actual ruler of the city was the French governor General Jean Rapp. The citizens had to accommodate Napoleon's forces and to pay large tributes in the preparation of the French invasion of Russia in 1812.