How did Otakar II expand the territory controlled by Bohemia?

Otakar II expanded the territory controlled by Bohemia through a combination of marriage, strategic invitations, and military campaigns, briefly establishing his kingdom as the most powerful state in the Holy Roman Empire.21

His territorial acquisitions included:

• Austria: He was elected duke of Austria in 1251 and later obtained further lands through marriage.21
• Styria: In 1260, he seized Styria from the Hungarians after being invited by the local nobility to become their overlord.21
• Alpine Provinces: Utilizing his personal bravery and significant financial resources, he took possession of Carinthia, Carniola, and Istria by 1269.21

By these means, his domains stretched from Silesia to the Adriatic Sea, earning him the reputation as the "king of iron and gold". However, this rapid expansion eventually led to conflict with Rudolf of Habsburg, resulting in the loss of these territories and Otakar's death at the Battle of Dürnkrut in 1278.21