Kingdom of Croatia (Medieval) in the context of "Battle of Gvozd Mountain"

Samuel (also Samoil or Samuil; Bulgarian: Самуил, pronounced [sɐmuˈiɫ]; Macedonian: Самоил/Самуил, pronounced [samɔˈiɫ/sɐmuˈiɫ]; Old Church Slavonic: Самоилъ; died 6 October 1014) was the Tsar (Emperor) of the First Bulgarian Empire from 997 to 6 October 1014. From 977 to 997, he was a general under Roman I of Bulgaria, the second surviving son of Emperor Peter I of Bulgaria, and co-ruled with him, as Roman bestowed upon him the command of the army and the effective royal authority. As Samuel struggled to preserve his country's independence from the Byzantine Empire, his rule was characterized by constant warfare against the Byzantines and their equally ambitious ruler Basil II.

In his early years, Samuel managed to inflict several major defeats on the Byzantines and to launch offensive campaigns into their territory. In the late 10th century, the Bulgarian armies conquered the Serb principality of Duklja and led campaigns against the Kingdoms of Croatia and Hungary. But from 1001, he was forced mainly to defend the Empire against the superior Byzantine armies. Samuel died of a heart attack on 6 October 1014, two months after the catastrophic battle of Kleidion. His successors failed to organize a resistance, and in 1018, four years after Samuel's death, the country capitulated, ending the five decades-long Byzantine–Bulgarian conflict.

Gregory of Nin (Croatian: Grgur Ninski pronounced [ɡr̩̂ɡuːr nîːnskiː]; Latin: Gregorius Ninnius) was a Croatian Catholic prelate who served as a medieval Bishop of Nin, whom strongly opposed the pope and official circles of the Catholic Church. He introduced the Croatian language in the religious services after the Great Assembly in 926, according to traditional Croatian historiography. Until that time, services were held only in Latin (being under the jurisdiction of Roman influence before the Great Schism), not being understandable to a majority of the population. Not only was this important for Croatian language and culture, but it also made Christianity stronger within the Croatian kingdom.