Pending the completion of their political organization, Bulgaria and Eastern Rumelia were occupied by Russian troops and administered by Russian officials. The assembly of notables, which met at Trnovo in 1879, was mainly composed of half-educated peasants, who from the first displayed an extremely democratic spirit, in which they proceeded to manipulate the very liberal constitution submitted to them by Prince Dondukov-Korsakov, the Russian governor-general. The long period of Turkish domination had effectually obliterated all social distinctions, and the radical element, which now formed into a party under Tzankoff and Karaveloff, soon gave evidence of its predominance. Manhood suffrage, a single chamber, payment of deputies, the absence of property qualification for candidates, and the prohibition of all titles and distinctions, formed salient features in the constitution now elaborated. The organic statute of Eastern Rumelia was largely modelled on the Belgian constitution. The governor-general, nominated for five years by the sultan with the approbation of the powers, was assisted by an assembly, partly representative, partly composed of ex-officio members; a permanent committee was entrusted with the preparation of legislative measures and the general supervision of the administration, while a council of six "directors" fulfilled the duties of a ministry.
On the 29th of April 1879 the assembly at Trnovo, on the proposal of Russia, elected as first sovereign of Bulgaria Prince Alexander of Battenberg, a member of the grand ducal house of Hesse and a nephew of the tsar Alexander II. Arriving in Bulgaria on the 7th of July, Prince Alexander, then in his twenty-third year, found all the authority, military and civil, in Russian hands. The history of the earlier portion of his reign is marked by two principal features - a strong Bulgarian reaction against Russian tutelage and a vehement struggle against the autocratic institutions which the young ruler, under Russian guidance, endeavoured to inaugurate. Both movements were symptomatic of the determination of a strong-willed and egoistic race, suddenly liberated from secular oppression, to enjoy to the full the moral and material privileges of liberty. In the assembly at Trnovo the popular party had adopted the watchword "Bulgaria for the Bulgarians," and a considerable anti-Russian contingent was included in its ranks.
Young and inexperienced, Prince Alexander, at the suggestion of the Russian consul-general, selected his first ministry from a small group of "Conservative" politicians whose views were in conflict with those of the parliamentary majority, but he was soon compelled to form a "Liberal" administration under Tzankoff and Karaveloff. The Liberals, once in power, initiated a violent campaign against foreigners in general and the Russians in particular; they passed an alien law, and ejected foreigners from every lucrative position. The Russians made a vigorous resistance, and a state of chaos ensued. Eventually the prince, finding good government impossible, obtained the consent of the tsar to a change of the constitution, and assumed absolute authority on the 9th of May 1881. The Russian general Ernroth was appointed sole minister, and charged with the duty of holding elections for the Grand Sobranye, to which the right of revising the constitution appertained. So successfully did he discharge his mission that the national representatives, almost without debate, suspended the constitution and invested the prince with absolute powers for a term of seven years (July 1881). A period of Russian government followed under Generals Skobelev and Kaulbars, who were specially despatched from St Petersburg to enhance the authority of the prince.
Their administration, however, tended to a contrary result, and the prince, finding himself reduced to impotence, opened negotiations with the Bulgarian leaders and effected a coalition of all parties on the basis of a restoration of the constitution. The generals, who had made an unsuccessful attempt to remove the prince, withdrew; the constitution of Trnovo was restored by proclamation (19th September 1883), and a coalition ministry was formed under Tzankoff. Prince Alexander, whose relations with the court of St Petersburg had become less cordial since the death of his uncle, the tsar Alexander II., in 1881, now incurred the serious displeasure of Russia, and the breach was soon widened by the part which he played in encouraging the national aspirations of the Bulgarians.