A year before the convention of the Erfurt Union Parliament, the May 26, 1849 Alliance of the Three Kings was concluded between Prussia, Saxony and Hanover, the latter two of which explicitly made the reservation of departure unless all other principalities with the exception of Austria joined. From this treaty sprung the Prussian policy of fusion, and thence the ambition of the Erfurt Union, which in its constitution abandoned universal and equal franchise in favour of the traditional three-class franchise. The constitution itself, however, was only to come into effect after revision and ratification by an elected Reichstag, as well as approval by the participating governments.