When the Latins seized temporal and spiritual power at Constantinople, the Serbian ruler Stefan Nemanja took the chance to throw off his vassal status. He pledged his support in arms to the Roman Catholic King of Hungary, then asked the papal legate to baptise him under the Roman rite. Thanks to this opportune change of faith, which does not appear in Serbian history books, the Nemanja dynasty built up a Serbian state that came to include most of Greece. However, Stefan Nemanja’s younger son, Sava kept to the Eastern faith, creating a Serbian Orthodox Church independent of Constantinople. Saint Sava, as he is known to his people, invented the slogan ‘Only Unity Saves Serbs’ (‘Samo Sloga Srbina Spasova’)‚
During the Middle Ages the idea arose that Croatia comprised not only the geographical heartland around Zagreb but all Roman Catholic Slavs who spoke Serbo-Croat. The Catholics in Slavonia, Dalmatia and Bosnia-Hercegovina who had previously thought of themselves simply as Slavs, or took their name from the clan or region, began to identify with the kingdom that ceased to exist in 1102.