In diplomatic history, the "Eastern Question" refers to the strategic competition and political considerations of the European Great Powers in light of the political and economic instability in the Ottoman Empire from the late 18th to early 20th centuries. Characterized as the "sick man of Europe", the relative weakening of the empire's military strength in the second half of the eighteenth century threatened to undermine the fragile balance of power system largely shaped by the Concert of Europe. The Eastern Question encompassed myriad interrelated elements: Ottoman military defeats, Ottoman institutional insolvency, the ongoing Ottoman political and economic modernization programme, the rise of ethno-religious nationalism in its provinces, and Great Power rivalries.
The Eastern Question is normally dated to 1774, when the Russo-Turkish War (1768–74) ended in defeat for the Ottomans. As the dissolution of the Ottoman Empire was believed to be imminent, the European powers engaged in a power struggle to safeguard their military, strategic and commercial interests in the Ottoman domains. Imperial Russia stood to benefit from the decline of the Ottoman Empire; on the other hand, Austria-Hungary and Great Britain deemed the preservation of the Empire to be in their best interests. The Eastern Question was put to rest after World War I, one of the outcomes of which was the collapse and division of the Ottoman holdings.
The Ottomans were at the height of their power in 1683, when they lost the Battle of Vienna to the combined forces of the Polish–Lithuanian Commonwealth and Austria, under the command of John III Sobieski. Peace was made much later, in 1699, with the Treaty of Karlowitz, which forced the Ottoman Empire to cede many of its Central European possessions, including those portions of Hungary which it had occupied. Its westward expansion arrested, the Ottoman Empire never again posed a serious threat to Austria, which became the dominant power in its region of Europe. The Eastern Question did not truly develop until the Russo-Turkish Wars of the 18th century.