Höbelt is a specialist in modern Austrian history at the University of Vienna with extensive publications in nineteenth- and twentieth-century political history, including a recent study of Jörg Haider. He also has published on the military history of the Thirty Years' War. Höbelt presents Ferdinand III as the “forgotten emperor” in the accounts of the rise of Habsburg Austria, caught between the historical reputations of his father, Ferdinand II, and his son, Leopold I. In truth, this is first full biography of Ferdinand III in any language. Höbelt's title suggests the tension that infuses his text. Ferdinand III, the “peace emperor,” is depicted in full armor on the biography's cover. This is also a classic biography, defined by the life of its subject, written in a breezy style seasoned with modern asides, and published to honor Ferdinand's 400th birthday. Nevertheless, the focus is not on politics or court culture, though these themes are addressed in context; rather, Höbelt focuses on Ferdinand and the Habsburg's extended family of kin, illegitimate offspring, and affines. Even noble advisors, ambassadors, and generals are presented as members of extended families. The Austrian Habsburgs governed in collaboration with noble dynasties, and the overlapping networks of patronage and intermarriage are spelled out in the text. Höbelt gives his players, both male and female, full voice through his use of their archival correspondence. The text presents a parade of characters interacting at the center of a political maelstrom, and even his index only covers persons, with a special section listing nearly four dozen Habsburgs.

By the reign of Charles V (Carlos I), the Habsburgs had built an empire through marriage alliances on which “the sun never set.” By Ferdinand III's birth, the extended family had split into two trunks, but intermarriage kept them tightly bound. Though Ferdinand's mother and grandmother were daughters of Bavarian Wittelsbach dukes, his first wife was his first cousin, Maria Anna of Spain, the youngest daughter of Philip III and Ferdinand's paternal aunt, Margaret. It is the tension between his close familial ties with Spain and the need to accept a peace with France that would abandon Spain that is the central way in which Ferdinand became the “peace emperor” against his will. As negotiations—both marital and political—unfold, the chapters skip from one seat of Habsburg familial power to another, with Vienna at the axis. As a younger son in a cadet line, young Ferdinand III appeared destined to the clergy. His grandfather and father were archdukes governing the dangerous Ottoman borderlands of Inner Austria from Graz. The fraternal strife between emperors Rudolph and Mathias, who had no heirs, brought the Inner Austrian Archduke forward to inherit the crowns of Bohemia, Hungary, and the Holy Roman Empire by 1619, but his position was dramatically undermined by powers bargained away to secure allies during the family feud. Ferdinand II and Ferdinand III would operate throughout their reigns from a position of comparative weakness. It is Ferdinand III's underappreciated great achievement that he left the Austrian core lands to Leopold in such strength.

It was also in 1619 that Ferdinand II's eldest son, Johann-Karl, died, which cut the younger Ferdinand's clerical career short, as he became heir-apparent to the Imperial throne. Dynastic needs defined his personal life from that point on. In 1631 the family elders arranged his marriage to his first cousin, Maria Anna, two years his senior, after five years of negotiation as complex as a peace treaty. Following her death, he negotiated his own marriage to Maria Leopoldine, daughter of his uncle Archduke Leopold of Austria, with her widowed mother, Claudia de Medici. Höbelt suggests that this marriage secured family solidarity within the Austrian circle at a critical point in the Westphalian negotiations. Ferdinand's third marriage in 1651, to Eleonora Gonzaga, Duchess of Mantua, secured ties with this Italian dynasty long attached to Habsburg interests. Faced with the need to separate himself politically from Spain as a condition for peace, in 1646, Ferdinand III proposed the marriage of his daughter, Mariana (age twelve), to Balthasar Carlos, the heir to the Spanish crowns, and his son, Ferdinand IV (age thirteen), to Balthasar Carlos's sister. The death of both princes ended the plan, though Mariana later married the prince's widowed father, Philip IV, her uncle, in 1649.

In Höbelt's account, war and peace are family affairs. Ferdinand II's military successes against Bohemian rebels and Imperial opponents during the 1620s depended on the support of his brother- and son-in-law, Maximilian I of Bavaria, and his Spanish cousins. The slow decline of Ferdinand III's military fortunes after 1635 is as much the result of the Spanish Habsburgs' weakness as Ferdinand's own setbacks against the Swedes. Early on in the Thirty Years' War, Höbelt argues that Ferdinand II's military and diplomatic policies revolved around efforts to secure his son's succession to the royal crowns in Hungary (1625) and Bohemia (1627). Moreover, securing support from the Imperial electors for Ferdinand III's candidacy as “King of the Romans” also drove Ferdinand II's decision to depose Wallenstein in 1630. Despite popular suspicion, Höbelt finds no evidence of Ferdinand III's direct role in Wallenstein's fall and assassination four years later. Ferdinand assumed Wallenstein's place, working closely with the lieutenants who had betrayed their general, yet the mercenary troops acquiesced to the change. Later at the battle of Nördlingen, Höbelt presents the future Emperor in full command of generals' conflicting egos as he turned over field operations to Matthias Gallas, who secured the great victory. Ferdinand III was an effective warrior, but he soon became attached to the peace party in Vienna during the last years of his father's life and made his historical mark—reluctantly—through his negotiations at Westphalia. In his first biography, Ferdinand III emerges as highly competent, devotedly Catholic, judiciously cautious, and most important willing to compromise. Höbelt has done his subject well and reminds us in his approach to Ferdinand the degree to which “reason of state” remained “reason of dynasty” in the seventeenth century.