Prussia’s great rival in the eighteenth century was Austria. Austria, as the ancestral state of the Habsburgs, had always been the single most powerful German state within the Holy Roman Empire. The Habsburgs, however, found that the diversity of their domains greatly hampered their ability to develop along absolutist lines. In some cases, they were able to reduce the power and independence of some of their nobles by supporting even more onerous control of peasants: for example, in Bohemia, peasants were made to work three days a week for their nobles, for free, and in return the Bohemian nobles allowed the emperor more control of the territory itself. In other territories like Hungary, however, nobles successfully resisted the encroachment of their Habsburg rulers.
The long-term pattern was that, especially after the Treaty of Westphalia that ended the Thirty Years’ War in 1648 rendered the political structure of the Holy Roman Empire virtually meaningless, “Habsburg” meant “Austrian.” The Habsburgs ruled Austria itself and exercised real control over the constituent kingdoms of their empire like Hungary and Bohemia, but had virtually no authority over the other Holy Roman states. With the Spanish branch of the family dying off in 1700 (the last Spanish Habsburg, Charles II, died without an heir in 1700), this identification was even stronger.