Svatopluk I

Svatopluk I or Zwentibald I was the ruler of Great Moravia that attained its maximum territorial expansion in his reign (869 or 870–871, 871–894). His career had already started in the 860s, when he governed a principality, the location of which is still a matter of debate among historians, within Moravia under the suzerainty of his uncle, Rastislav. Svatopluk dethroned Rastislav, who was a vassal of Louis the German and betrayed him to the Franks in 869 or 870, but in a year he was also imprisoned by them.

Having been released due to the Moravians' rebellion against the Franks, Svatopluk joined the rebels and defeated the invaders. Although he was obliged to pay tribute to East Francia according to the peace treaty concluded at Forchheim (Germany) in 874, he was able to expand in territories outside the Franks' sphere of interest in the following years. His forces even invaded the March of Pannonia within East Francia in 882.

Svatopluk established good relationship with the popes, thus he and his people were taken under the protection of the Holy See in 880. Pope Stephen V even addressed him "king" in a letter written in 885. In matters of religion, Svatopluk wanted to appease the German clergy who opposed the liturgy officiated in Old Church Slavonic; therefore Methodius's disciples were expelled from Moravia in 886, after their teacher's death.

Svatopluk's state was a loose structure of principalities and also included conquered territories. Not long after his death Svatopluk's "Great Moravia", as the Byzantine Emperor Constantine VII Porphyrogenetos would refer to it around 950, collapsed due to the power struggle between his sons and the intensifying Hungarian raids. Svatopluk whose empire encompassed the whole or parts of the territory of modern Slovakia has time to time been presented as a "Slovak king" in literary works since the 18th century, the period of the Slovak national awakening.