In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Q: For his actions in World War II, one ruler of this country may have been poisoned by Hitler for his efforts to save his country's Jews. This country, once ruled by Ferdinand and Boris, considers its "Second National Catastrophe" to be losses suffered in the Treaty of Neuilly-sur-Seine. During the 1876 April Uprising in this future nation, Ottoman forces committed massacres in the Plovdiv area in this country's namesake "horrors." People from this nation were defeated at the Battle of Kleidion, which saw 99 out of 100 men blinded. For 10 points, name this eastern European nation whose peoples were notably fought by the Byzantine Basil II.
A:
History