Oñate treaty

[4] As head of Matthias' Secret Council, Klesl was working to facilitate a reconciliation between Catholics and Protestants in Austria,[5] hoping to prevent a continued paralysis of the Holy Roman Empire's institutions: the Reichstag was unable to convene in 1608 and 1613, and the common Türkenhilfe defense against the Ottoman threat was at risk.

[5] Cardinal Klesl knew that Ferdinand II favoured the Counter-Reformation, which aimed to address some of the Church's institutional problems that had been raised by the Protestant noblemen whose support was instrumental to the Holy Roman Empire's operations.

[7] Philip also wanted to strengthen his position in Italy by acquiring principalities around its Duchy of Milan and by gaining direct access to the Mediterranean Sea via towns like Finale Ligure, allowing it to bypass the Republic of Genoa.

[3] Philip III agreed to renounce his claims to the thrones of Bohemia and Hungary,[10] so long as the princes of the Kingdom of Germany did elect Ferdinand II as ruler of the Holy Roman Empire upon the death of Emperor Matthias.

[3] In return, Ferdinand II promised Philip III the town of Finale Ligure, the Principality of Piombino (both of which were already occupied by Spain), as well as cession of Austrian Habsburg rights to Ortenau and Alsace.

[13] The events in Bohemia resulted in mobilization of the German Catholic League, and with Spanish support, Ferdinand II defeated the Bohemian estates and expelled the "winter king" in the Battle of White Mountain on 8 November 1620.