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The legitimacy of the succession was recognized by the Emperor Rudolph II but not by Pope Clement VIII: thus, as Ferrara was nominally a Papal fief, the city was returned to the Papal States, despite the attempts of the young duke, who sought help from the Major Powers to no avail.
The situation was further complicated by acquisitive desires of Emperor Rudolph II and the Wettin dukes of Saxony — the former particularly worrying to Henry IV of France and the Dutch Republic, who feared any strengthening of the Habsburg Netherlands.