 At the same time, the Porte made several concessions to the rulers and boyars of Moldavia and Wallachia, as a means to ensure the preservation of its rule.The Treaty of Küçük Kaynarca, signed in 1774 between the Ottomans and Russians, gave Russia the right to intervene on behalf of Eastern Orthodox Ottoman subjects in general, a right which it used to sanction Ottoman interventions in the Principalities in particular.Thus, Russia intervened to preserve reigns of "hospodars" who had lost Ottoman approval in the context of the Napoleonic Wars (the "casus belli" for the 1806–12 conflict), and remained present in the Danubian states, vying for influence with the Austrian Empire, well into the 19th century and annexing Moldavia's Bessarabia in 1812.