Frederick was the son of Ulrich of Sanneck, Lord of Žovnek. His father was a free noble in the March on the Savinja, a region fragmented among various small estates, which was contested between the House of Gorizia-Tyrol and the Habsburgs. Frederick's father took the side of the Habsburg dukes of Styria, becoming their vassal. His allegiance was instrumental in the incorporation of the Savinja Valley into the Duchy of Styria and thus into the Habsburg domains. Frederick's mother was Catharine, the firstborn daughter of Ulrich IICount of Heunburg and of Agnes of Baden. Ulrich of Heunberg owned important estates in Carinthia, Carniola and Styria, while Agnes was the titular heiress of the House of Babenberg through her mother Gertrude of Austria. Both of Frederick's parents died around 1315, and he became the head of the house. In 1322, the male line of the Counts of Heunburg became extinct, and Frederick inherited the estates from his maternal uncle Hermann. However, he had to contend the inheritance with his cousin Ulrich V. of Pfannberg, son of Count Hermann's younger sister Margaret. He also had to deal with the dowager countess Elizabeth, daughter of the powerful Albert II of Gorizia, who claimed part of her late husband's estates. After a protracted legal and military struggle, Frederick prevailed with the help of his brother-in-law Ulrich von Walsee, captain of Styria, who enjoyed the support of the reigning duke Otto the Merry. By 1333, Frederick was in possession of almost all of the Heunburg estates. Frederick followed his father's policy of allegiance to the Habsburgs. In the early 1330s, he was named captain of Carniola and the Windic March, preparing the ground for a smooth transition of power from duke Henry of Bohemia, the last male member of the Gorizia-Tyrol dynasty, to the Habsburgs. When the Habsburgs did take over Carniola in 1335, Frederick was confirmed in his position. As a reward for his loyalty, the Habsburgs gave their consent for Frederick's elevation to the status of count. In April 1341, he was granted the title of Count of Celje by the Holy Roman Emperor Louis IV in a ceremony in Munich. Shortly before his death, he took part of a diplomatic mission on behalf of Albert II, Duke of Austria and the Hungarian kingLouis the Great to the papal court in Avignon.
Policy of expansion
Slovenian historian Milko Kos called Frederick "the first architect of the Celje glory", claiming that "he possessed all those abilities in statesmanship that would characterize his greatest successors". By the time of his death, he was one of the most powerful feudal lords in the territory of present-day Slovenia, rivaled only by his Habsburg liege lords, the Albertine line of the Counts of Gorizia and the Counts of Ortenburg. Frederick pursued a strategy of alliance with the latter: his first born son Ulrich would marry Adelaide, daughter of Count Albert I of Ortenburg, while her brother and Albert's successor Otto VI married Frederick's daughter anna. The arrangement would prove very beneficious to the Counts of Celje, as they would inherit all Ortenburg possessions in Carinthia and Carniola after the death of Frederick's grandson and namesake Frederick III of Ortenburg in 1418. Frederick's fiefs and allods covered almost the entire territory of the former March on the Savinja, safe for scattered ecclesiastical lands. In addition to that, he acquired vast areas in the wealthy Krka Valley and the Heunburg original territories around Heunburg in southeastern Carinthia. He was succeeded by his sons Ulrich and Hermann I.
Marriage and children
Frederick married Diemut of Wallsee. Four of their children survived into adulthood:
Ulrich, married countess Adelaide of Ortenburg, had issue;
