The Great Interregnum ends with the unanimous election of Rudolph I of Habsburg, a minor pro-Staufen count, as German king at Frankfurt.

A son of Austria’s Albert IV, Count of Habsburg, Rudolph cements his conquest of the ambitious Ottokar of Bohemia through strategic marriage contracts for his children, and grants his son Albrecht (Albert) the duchies of Austria and Styria, making these possessions hereditary fiefs that will constitute the territorial nucleus of the future Habsburg power.

The House of Kyburg, a family of Grafen or counts from Zürich in Switzerland, is one of the three most powerful noble families in the Swiss plateau beside the Habsburg and the House of Savoy during the eleventh and twelfth centuries.

With the extinction of the male line in 1263, Rudolph of Habsburg lays claim to the Kyburg lands and in 1264 annexes them to the Habsburg holdings, which marks the beginning of the Habsburg rise to power.

In the same year, Winterthur gains city rights from the new owners, and the city’s Church of Sankt Laurenz is constructed.

The fortunes of King Ottokar II of Bohemia had changed soon after the 1273 election of Rudoph, a son of Albert IV, Count of Habsburg, as German king at Frankfurt, hastened by the desire of the electors to exclude Ottokar, an increasingly powerful rival candidate of non-German birth.

Following his coronation as King of Germany on October 24, 1273, Rudolph launches a campaign to revive the monarchy's prestige and to recover alienated fiefs.

He claims Austrian territory as his imperial right, but Ottokar II has annexed much of it, including Austria, Styria, Carinthia, Carniola, and Istria, to Bohemia.

Alfonso X of Castile, having spent great sums vainly trying to gain recognition as Holy Roman Emperor, protests the election in 1273 of Rudolf of Habsburg as King of Germany.

Pope Gregory X convinces Alfonso to relinquish his claim in returns for Rudolf’s renunciation of his claims to Rome or the Papal States.

Rudolph of Habsburg, to win the approbation of Pope Gregory X, had renounced all imperial rights in Rome, the papal territory, and Sicily, and promised to lead a new crusade.

The Pope, in spite of Ottokar II of Bohemia's protests, not only recognizes Rudolph himself, but persuades King Alfonso X of Castile (another grandson of Philip of Swabia), who had been chosen German (anti-)king in 1257 as the successor to Count William II of Holland, to do the same.

Thus, Rudolph surpasses the two heirs of the Hohenstaufen dynasty that he had earlier served so loyally, and succeeds in saving the Holy Roman Empire from disintegrating by promoting the election of Rudolf I of Habsburg as emperor.

At the same time, he keeps the peace with King Charles I of Naples, who also has claims on the imperial throne.

In return for his support, Gregory makes Rudolph promise to lead a new crusade and to renounce claims on behalf of the Holy Roman Empire in Rome and the papal territories.

Rudolph, a son of Albert IV, count of Habsburg, whose family dates back to the tenth century with possessions in Switzerland and Alsace, had in 1268 been elected as the successor to Hohenstaufen king Conradin, although King Ottokar II of Bohemia, the most powerful prince in the Holy Roman Empire, is a leading contender.

Rudolf himself, who holds scattered lands in the Upper Rhineland and Switzerland, is on September 29, 1273, crowned at Aachen, ending the Interregnum.

Otakar’s refusal to acknowledge Rudolph as the new king will lead in 1276 to the outbreak of war.

Ottokar, refusing to recognize his victorious rival, Rudolf of Habsburg, and urging the Pope to adopt a similar policy, incurs the enmity both of rival princes and of his own nobility.

At a convention of the Imperial Diet at Nuremberg in 1274, Rudolf decrees that all imperial lands that had changed hands since the death of Emperor Frederick II must be returned to the crown.

This would deprive Ottokar of Styria, Austria, and Carinthia.

Almost all European rulers agree, with the notable exception of Ottokar.

Pope Gregory X decrees in 1274 that conclaves (meetings during which the electors have no contact with the outside) should be used for papal elections, reforming the electoral process which had taken over three years to elect him.

In this same year, he issues a bull denying the existence of ritual murders by Jews.

Following his pleas at the Council of Lyons in 1274, Gregory discovers that, although Europe is aware of the gravity of the Eastern situation, it is both unwilling and unable to give substantial aid.

East Central Europe (1276–1287 CE): Fall of Ottokar II, Rise of the Habsburgs, Continued Hungarian Turmoil, Polish Duchies' Independence, and Strengthening Thuringian and Saxon Influence

Between 1276 and 1287 CE, East Central Europe experienced transformative shifts following the dramatic fall of Bohemia's powerful ruler, Ottokar II Přemysl, the consequent rise of the Habsburg dynasty in Austria, continued fragmentation in Poland, persistent internal instability in Hungary, and strengthened regional influence of Saxon and Thuringian principalities. This period redefined political alignments, setting critical foundations for subsequent medieval geopolitical and cultural developments.

Political and Military Developments

Ottokar II’s Fall and the Habsburg Rise

• In 1278, at the decisive Battle on the Marchfeld, Ottokar II Přemysl of Bohemia was defeated and killed by Rudolf I of Habsburg. This battle dramatically shifted regional dominance, ending Přemyslid authority over Austria, Styria, and Carinthia.

• The victory secured Austria for the emerging Habsburg dynasty, establishing a territorial foundation crucial for their subsequent centuries-long dominance in Central European politics.

Instability and Succession Conflicts in Bohemia

• Ottokar's son, Wenceslaus II (r. 1278–1305), ascended as a minor, triggering internal instability and noble infighting within Bohemia. Royal authority significantly weakened, necessitating regency councils and external diplomatic interventions.

Hungarian Continued Aristocratic Fragmentation

• Hungary remained troubled by aristocratic factionalism and regional conflicts following the brief reigns of Stephen V (r. 1270–1272) and his son Ladislaus IV "the Cuman" (r. 1272–1290). Royal authority struggled against powerful nobles, significantly weakening Hungary’s ability to assert regional influence.

Polish Duchies and Continued Fragmentation

• Polish territories remained fragmented into multiple independent Piast duchies, notably in Silesia, Greater Poland, and Mazovia. Despite political division, economic prosperity continued, driven by growing urbanization, Hanseatic trade, and local autonomy.

Thuringian Consolidation and Wettin Influence

• Following their triumph in the Thuringian Succession War (ending 1264), the Wettin family solidified their authority over Thuringia, expanding their regional influence. Thuringia's stability allowed it to exert political and cultural influence within the eastern German sphere.

Saxon Territories and Emerging Dynastic Influence

• The Saxon duchies and principalities, especially the Wettin-controlled territories and the emerging power of Saxe-Wittenberg, increasingly asserted influence within East Central Europe, fostering economic growth, urban expansion, and political stability.

Brandenburg Expansion and Consolidation

• Under the House of Ascania, Brandenburg continued territorial consolidation eastward into former Slavic lands. Their settlements strengthened economic and demographic integration into broader Central European networks.

Economic and Technological Developments

Urban and Commercial Growth

• Economic prosperity continued across East Central Europe, driven by robust Hanseatic League trade, connecting Baltic markets to broader European economies. Cities such as Lübeck, Rostock, Toruń, Kraków, and Wrocławflourished economically, becoming vibrant urban centers.

Agricultural Productivity Enhancements

• Improved agricultural techniques and tools, including more efficient plows and extensive use of the three-field rotation system, increased productivity and regional population growth, fueling urban development.

Cultural and Artistic Developments

Bohemian Cultural Continuity Despite Political Instability

• Although politically weakened, Bohemia maintained a thriving cultural life centered on Prague. Gothic architecture, manuscript illumination, and literature continued flourishing, influenced by earlier Přemyslid patronage.

Regional Artistic Flourishing in Polish Duchies and Hungary

• Silesian and Polish duchies retained cultural dynamism, evident in ecclesiastical architecture, monasteries, and manuscript production, notably in Wrocław and Kraków.

• Despite political turmoil, Hungarian ecclesiastical institutions continued fostering cultural and artistic patronage, maintaining religious and intellectual continuity.

Settlement and Urban Development

Continued Urban Expansion and Fortification

• Urban growth and fortifications expanded significantly throughout Austria, Bohemia, Poland, and Saxon territories, bolstering regional economic prosperity, political influence, and demographic stability.

Intensified Germanic Settlement (Ostsiedlung)

• Ongoing Germanic colonization in Brandenburg, Mecklenburg, Silesia, and Lusatia profoundly influenced demographic patterns, urban development, and agricultural innovation, reshaping local economies and identities.

Social and Religious Developments

Increased Ecclesiastical Influence

• Ecclesiastical institutions, notably the Archbishopric of Salzburg and bishoprics of Bamberg, Passau, and Regensburg, expanded their social and cultural influence, promoting education, religious life, and artistic patronage.

Aristocratic Autonomy and Feudal Structures

• Aristocratic and noble autonomy strengthened significantly, especially in Hungary, Bohemia, and Polish duchies. Local noble authority increasingly dominated political and economic governance, setting firm foundations for regional identities and power structures.

Long-Term Consequences and Historical Significance

The era 1276–1287 CE profoundly reshaped East Central Europe. The fall of Ottokar II and rise of the Habsburgs fundamentally altered regional power dynamics, setting the stage for long-term Austrian dominance. Continued Hungarian aristocratic factionalism weakened royal centralization, while Polish fragmentation deepened local autonomy. Wettin-controlled Thuringia and Saxon territories expanded their regional influence, significantly shaping future political developments. Economically, intensified trade, urbanization, and agricultural innovation brought lasting prosperity and cultural flourishing. Collectively, these transformations firmly established the geopolitical and cultural framework for subsequent medieval developments throughout East Central Europe.

Ottokar II, King of Bohemia, had at the height of his power aimed at the Imperial crown, but the Princes-Electors (Kurfürsten), distrustful of his steep rise, had elected the "poor Swabian count" Rudolph of Habsburg King of the Romans on September 29, 1273.

As the election had taken place in his absence, Ottokar did not acknowledge Rudolph as King.

Rudolph himself had promised to regain the "alienated" territories which had to be conferred by the Imperial power with consent of the Prince-electors.

He claimed the Austrian and Carinthian territories for the Empire and summoned Ottokar to the 1275 Reichstag at Würzburg.

By not appearing before the Diet, Ottokar had set the events of his demise in motion.

Placed under the Imperial ban in June 1276, he has had all his territorial rights revoked, including even his Bohemian inheritance.

Meanwhile, Rudolph is gathering allies and preparing for battle.

He achieves two of these alliances through the classic Habsburg style—marriage.

First, he marries his son Albert to Elisabeth of Gorizia-Tyrol.

In return, her father Count Meinhard II of Gorizia-Tyrol receives the Duchy of Carinthia as a fief.

Second, he establishes an—unstable—alliance with Duke Henry I of Lower Bavaria by offering him his daughter Katharina as wife for his son Otto in addition to the region of present-day Upper Austria as a pledge for her dowry.

He also concludes an alliance with King Ladislaus IV of Hungary, who intends to settle old scores with Ottokar.

So strengthened, Rudolph besieges Ottokar at the Austrian capital Vienna in 1276.

Many Austrian nobles chafe under Ottokar's rule; some have been executed for insurgence The Bavarian knights seize the amply provisioned center of Klosterneuberg near Vienna, and use the captured supplies to sustain Rudolph’s forces during the siege.

Ottokar had recently fortified the city, but his troops prove disloyal and desert.

He is forced to surrender and to renounce all his acquisitions, receiving only Bohemia and Moravia as a fief from King Rudolph.

Heavily deprived by this, he is determined to regain his territories and contracts an alliance with the Ascanian Margraves of Brandenburg and the Polish princes.