The Balkans is the region that the Ottomans called Rumelia. The Balkans, which was a part of the Ottoman Empire, witnessed very heated events throughout the 19th century. Numerous rebellions broke out, and many Balkan nations struggled for independence. The Ottoman-Russian War of 1877-1878 was one of the important events of the 19th century and was a turning point in the history of the Balkan nations. It will be 145 years in 2022 from the date of the start of this war, which is also a touchstone in terms of Ottoman history, Balkan history, war history and international relations. The preparation of an issue covering the causes, beginning and outcome of the Ottoman-Russian War will provide important contributions to the commemoration of this war. Our aim is to collect current studies on this subject in different social sciences in one volume. This war has many fronts in the Balkans. It is aimed to illuminate issues such as how the war took place on these fronts, what developments it led to, and the importance of the San Stefano and Berlin Agreements made as a result of the war. Studies on the activities of the commanders who took part in this war such as Osman Pasha, Skobelev, Gurko will also be included. There are many documents in the world archives on this subject that have not been examined yet. In addition, there are many unexamined memoirs of the war in various libraries. Evaluating these and presenting new studies will illuminate the historical events in the second half of the 19th century. One of the important results of the Ottoman-Russian War was that it caused a great population mobility and caused the migration of masses of people from the Balkans to Anatolia. The dimensions of this migration will be one of the issues examined.