The 'Millet' concept that was supposed to bring unity to the Ottoman Empire slowly faded away with the rise of nationalism - and that is what is so interesting about the paradox! Earlier the concept of nationalism came from the roots of religion and it was not until the late 17th and early 18th century when the roots shifted from religion to nationalist. That is when people started recognizing the whole region and country as a whole. The region was totally under control and was united but the later incumbency of rulers led the masses into believing that it was the right time for the nationalist movements to take place.
The Balkan Region and Nationalism
With so many ethnic groups under its umbrella, different groups had their own views on nationalism; a melting pot of various cultures however did not see the homogenous mixing of everybody's version of nationalism into a single concept. To understand the outcome of the single concept, one must go through the different nationalist ideologies of different ethnic groups of the Ottoman Empire.
The war of 1877 with Russia marked a new low in the strategic military ability of the Ottoman Imperial forces. With Russia having dealt a decisive blow, the power in the Balkan region weaned and Ottoman was left with the region of Macedonia and Albania. The fear of partition brought the Albanians together and hence the reason of the Albanian concept of nationalism sprouted aftermath the war with Russia.
When considering the Arabic regions, their concept of nationalism arose from the fact that in region from Arab to Morocco, people had similar identity, spoke the same language and had the same view and therefore the annexure to the Ottoman Empire was unworthy. However, the rise of Arabic nationalism was quite late and it was not until the early 20th century when they pushed for their freedom. Nationalism of different groups threatened the existence and unity of Ottoman Empire.
Armenians - when they started being marginalized by the original Ottoman people decided a nationalist movement against the state that they termed as their freedom movement. However, with mass support the state ordered the execution of the Armenians that led to the Ottoman genocide episode. However, it was not until things began going out of control when the Ottoman state openly waged a war against the Armenians. The Jewish too got their share of Promised Land from the Ottoman Empire that is modern day Israel. Similarly, Kurds, Serbians, Turks and other groups also asserted their nationalism principles.