introduces
Eleonora of Portugal to Frederick III'' by
Pinturicchio (1454–1513) Frederick's political initiatives were hardly bold, but they were still successful. Frederick III was crowned Holy Roman Emperor in 1452, the first since the death of Emperor
Sigismund. His ascension to the role of Emperor came with the stipulation that should the previous queen of Bohemia (wife of Albert V of the Albertine line) give birth to a male heir, Frederick would become his guardian. When the queen gave birth to
Ladislaus the Posthumous, as according to the stipulations, Frederick took on his guardianship. This led to conflicts between Frederick and other members of the royal family and nobility. His first major opponent was his brother
Albert VI, who challenged his rule. He did not manage to win a single conflict on the battlefield against him, and thus resorted to more subtle means. He held his
second cousin once removed Ladislaus the Posthumous, the ruler of the
Archduchy of Austria, Hungary and Bohemia, (born in 1440) as a prisoner and attempted to extend his guardianship over him in perpetuity to maintain his control over
Lower Austria. Ladislaus was freed in 1452 by the Lower Austrian estates. He acted similarly towards his first cousin
Sigismund of the Tyrolian line of the Habsburg family. One of his important advisors during this time was
Friedrich II von Graben. Ultimately, Frederick prevailed in all those conflicts by outliving his opponents and sometimes inheriting their lands, as was the case with Ladislaus, from whom he gained Lower Austria in 1457, and with his brother Albert VI, whom he succeeded in
Upper Austria. In 1462, his brother Albert raised an insurrection against him in
Vienna and the emperor was besieged in his residence by rebellious subjects. In this war between the brothers, Frederick received support from the King of Bohemia,
George of Poděbrady. These conflicts forced him into an anachronistic itinerant existence, as he had to move his court between various places through the years, residing in
Graz,
Linz and . owes him its castle and the "New Monastery". In 1469 Friedrich founded the
Order of St. George, which still exists today, whereby the first investiture in the
Lateran Basilica in Rome was carried out by him and
Pope Paul II. The
Ottoman conquest of Bosnia in 1463 brought their frontier closer to the Habsburg lands, setting the stage for more intense
incursions. The Ottoman Turks raided
Carniola in 1469 and launched almost annual raids into
Styria after 1471.
Carinthia saw five Turkish incursions into its territory between 1473 and 1483, with much plundering and killing at the hands of Ottoman cavalry. These raids led to the
Carinthian Peasant Revolt of 1478, as peasants, left unprotected by the nobility, tried to defend themselves and formed a peasants' league to organize their own defense. The raids also prompted the construction of defensive structures like fortified churches and castles (tabor). In 1491, Ottoman raids in the Habsburg territories of Styria and Carniola ended after a significant defeat at the
Battle of Vrpile.
Mary of Burgundy, sole heir to the rich Burgundian kingdom, after the death of her father
Charles the Bold, soon made her choice among the many suitors for her hand by selecting Archduke Maximilian of Austria, the future Holy Roman Emperor Maximilian I (son of Frederick III) who became her co-ruler. With the inheritance of
Burgundy, the House of Habsburg began to rise to predominance in Europe. This gave rise to the saying "Let others wage wars, but you, happy Austria, shall marry", which became a motto of the dynasty. Frederick secured in 1486 the succession of the son in his own lifetime. On 16 February 1486 Maximilian was unanimously elected Roman-German king at the Frankfurt Reichstag by the six electors present. The Elector of Bohemia was not invited because the Bohemian spa law might have been claimed by the Hungarian King Corvinus. There are still discussions regarding whether Frederick actively provided the initiative for his son's election or not. As Frederick's only surviving male heir though, Maximilian was a natural choice for Frederick and the Estates to counter Hungary's ambitions. On the occasion of the election of Maximilian, a ten-year land peace was decided. In order to safeguard the peace of the land and against the expansive territorial policy of the
House of Wittelsbach, numerous affected empire-related states of Swabia joined in 1488 on Frederick's initiative for the
Swabian League. After the royal election Frederick accompanied his son to
Aachen, where Maximilian was crowned on 9 April 1486. There seemed to be tensions between father and son due to differences in personalities and leadership styles. But Frederick saw Maximilian's values in negotiating with the Estates, thus even though he was wary of infringements on his imperial power, Maximilian quickly became an essential partner in imperial politics. In 1487, his daughter
Kunigunde married
Albert IV, Duke of Bavaria. Albert illegally took control of some imperial
fiefs and then asked to marry Kunigunde (who lived in Innsbruck, far from her father), offering to give her the fiefs as a
dower. Frederick agreed at first, but after Albert took over yet another fief,
Regensburg, Frederick withdrew his consent. On 2 January 1487, however, before Frederick's change of heart could be communicated to his daughter, Kunigunde married Albert. A war was prevented only through the mediation of the Emperor's son, Maximilian. In some smaller matters, Frederick was quite successful: in 1469 he managed to establish
bishoprics in
Vienna and , a step that no previous Duke of Austria had been able to achieve. Frederick failed to gain control over
Hungary and
Bohemia in the
Bohemian–Hungarian War (1468–78). Frederick proclaimed himself King of Hungary on 27 February 1459, but this did not intimidate
Mathias Corvinus. Frederick decided to invade, but his army never got far, as he was no general. From Mantua,
Pius II (who was also Frederick's former secretary) urged the Emperor to leave Mathias alone. Hungary, he proclaimed, "is the shield of all Christendom under cover of which we have hitherto been safe. [...] If the road is thus opened to the barbarians, destruction will break in over all and the consequences of such a disaster will be imputed by God to its authors." Frederick was even defeated in the
Austrian–Hungarian War (1477–88) by
Matthias Corvinus in 1485, who managed to maintain residence in
Vienna until his death five years later in the
Siege of Vienna. Emperor Frederick failed to procure help from the
Prince-electors and the
Imperial States. In 1483 he had to leave his
Hofburg residence in
Vienna and fled to
Wiener Neustadt, where he also was besieged by Matthias' troops for 18 months until the fortress was captured in 1487. Humiliated, Frederick fled to
Graz, and later to
Linz in
Upper Austria. Frederick's personal motto was the mysterious string
A.E.I.O.U., which he imprinted on all his belongings. He never explained its meaning, leading to many different interpretations being presented, although it has been claimed that shortly before his death he said it stands for '
or ' ("All the world is subject to Austria"). It may well symbolise his own understanding of the historical importance and meaning of his rule and of the early gaining of the Imperial title. After 1440, the reform of the Empire and Church was sustained and led by local and regional powers, particularly the territorial princes. In his last years, however, there was more pressure on him taking action from a higher level.
Berthold von Henneberg, the Archbishop of Mainz, who spoke on behalf of reform-minded princes (who wanted to reform the Empire without strengthening the imperial hand), capitalized on Frederick's desire to secure the imperial election for Maximilian. Thus in his last years, he presided over the initial phase of Imperial Reform, which would mainly unfold under his son Maximilian. Maximilian himself was more open to reform, although naturally he also wanted to preserve and enhance imperial prerogatives. After Frederick retired to Linz in 1488, as a compromise, Maximilian acted as mediator between the princes and his father. When he attained sole rule after Frederick's death, he would continued this policy of brokerage, acting as the impartial judge between options suggested by the princes. ==Patronage of the arts==