(See The Timeline for part I.)
(See The Context for part II.)
West European intervention in the Balkans up until the 1880s worked well toward its desired outcome. The extent of Ottoman retreat was less than would have been without the involvement of the Western powers. Russia in this period demonstrated both the willingness to fight the Ottoman Empire and the ability to defeat it. Had the West Europeans stood aside Russia would have almost certainly be able to free the region from the Turks and pave the way for the establishment of independent Balkan national states. As it was the completion of liberation of the Balkan's Christians had to wait for several decades more and had to be achieved by the Balkan peoples themselves.
The decisive West European intervention in 1878 in Berlin meant the Balkan peoples were to derive only minimal benefit from the Russian victory in the 1877-78 Russian-Turkish war which Russia had fought more for their benefit than its own. Before that European stance in international diplomacy and the consequences and the memory of its invasion of Russia in the Crimean War kept St. Petersburg from perhaps launching a general attempt at freeing the Balkan peoples not in 1877, but perhaps earlier in the 1860s or the 1850s.
Western meddling thus made much of the sacrifice of the Russian soldier in 1877 in vain and prolonged Ottoman oppression and human tragedy in the Balkans for a further generation – until the region was freed of its imperial overlords with the First Balkan War in 1912. As H. N. Brailsford noted a century ago:
"We did not think that the affairs of Turkey were no concern of ours in 1878, when we tore up the Treaty of San Stefano and were ready to use "the ships, the men," and "the money too" in order to prevent the liberation of Macedonia by its inclusion in a free Bulgaria. The actual situation is of our making, and the Macedonians have endured a generation of oppression because we conceived that their emancipation was inconsistent with our own Imperial interests."
The Balkan Christian nations in this period demonstrated their desire to be freed of Turkish rule and their willingness to take up arms and fight to this end. However they were not jet strong enough to eject the Turks on their own. Thus while Western intervention in this time greatly limited the extent of liberation won for the Balkans by Russia it can not be said to had thwarted its liberation by its native peoples.