returned once more to the Habsburgs. Although Albert himself only reigned for a year (1438–1439), from then on, every emperor was a Habsburg (with only one exception: Charles VII 1742–1745), and Austria's rulers were also the Holy Roman Emperors until its dissolution in 1806. Archduchy of Austria: Becoming a Great Power (1453–1564) Frederick V (1453–1493): Elevation of the duchy Frederick V (Duke 1424 Archduke 1453, died 1493) the Peaceful (Emperor Frederick III 1452-–1493) confirmed the Privilegium Maius of Rudolph IV in 1453, and so Austria became an official archduchy of the Holy Roman Empire, the next step in its ascendancy within Europe, and Ladislaus the Posthumous (1440–1457) the first official archduke for a brief period, dying shortly after. The document was a forgery, purportedly written by the Emperor Frederick I and "rediscovered". Frederick had a clear motive for this. He was a Habsburg, he was Duke of Inner Austria in addition to being Emperor, and, up till the previous year, had been guardian of the young Duke of Lower Austria, Ladislaus. He also stood to inherit Ladislaus's title, and did so when Ladislaus died four years later, becoming the second Archduke. The Austrian Archdukes were now of equal status to the other Prince Electors that selected the emperors. Austrian governance was now to be based on primogeniture and indivisibility. Later Austria was to become officially known as "Erzherzogtum Österreich ob und unter der Enns" (The Archduchy of Austria above and below the Enns). In 1861 it was again divided into Upper and Lower Austria. The relative power of the emperor in the monarchy was not great, as many other aristocratic dynasties pursued their own political power inside and outside the monarchy. However Frederick, although lackluster, pursued a tough and effective rule. He pursued power through dynastic alliances. In 1477 Maximilian (Archduke and Emperor 1493–1519), Frederick's only son, married Mary, Duchess of Burgundy, thus acquiring most of the Low Countries for the family. The strategic importance of this alliance was that Burgundy, which lay on the western border of the empire, was demonstrating expansionist tendencies, and was at that time one of the richest and most powerful of the Western European nation states, with territories stretching from the south of France to the North Sea. The alliance was achieved at no small cost, since France, which also claimed Burgundy, contested this acquisition, and Maximilian had to defend his new wife's territories