The elements at hand for the construction of the constitution of the Empire were four: (1) the constitution of the North German Confederation, in operation since 1867; (2) the treaties of November 15, 1870, between the Confederation, on the one hand, and the grand-duchies of Baden and Hesse on the other; (3) the treaty of November 23, 1870, by which was arranged the adhesion of the kingdom of Bavaria; and (4) the treaty of November 25, 1870, between the _Bund_, Baden, and Hesse, on the one side, and the kingdom of Wuerttemberg on the other. Each of these treaties stipulated the precise conditions under which the new affiliation should be maintained, these stipulations comprising, in effect, so many projected amendments of the original constitution of the _Bund_.[282] At the initiative of the Emperor there was prepared, early in 1871, a revised draft of this constitution, and in it were incorporated such modifications as were rendered necessary by the adhesion of the southern states and the creation of the Imperial title. March 31 the Reichstag was convened in Berlin and before it was laid forthwith the constitutional _projet_, to which the Bundesrath had already given its assent. April 14 the instrument was approved by the popular chamber, and two days later it was promulgated as the supreme law of the land. [Footnote 282: The first three of these treaties were concluded at Versailles; the fourth was signed at Berlin.]