His paternal grandparents were Count Siegmund Andreas Corsinus Berchtold von und zu Ungarschitz and Countess Ludmilla Maria Theresia Wratislavová z Mitrowicz.

[1] In September 1908, he hosted a secret meeting between Aehrenthal and the Russian Foreign Minister Alexander Izvolsky at his estate at Buchlau in Moravia.

[5] At the death of Aehrenthal in February 1912, Count Berchtold was appointed as his successor and thus became, at the age of 49, the youngest foreign minister in Europe.

[1] Count Berchtold's focus on Serbia was grown out of a fear of Serbian territorial expansion in the Balkans and also a complication of frictional matters within the multinational Dual Monarchy, and would eventually result in the dissolution of the empire itself.

[9] Following the Balkan Wars, the assassination of Archduke Franz Ferdinand at Sarajevo on 28 June 1914 was therefore a culmination of the heightened tension between Austria-Hungary and Serbia.

[8] If Count Berchtold had been accused of indecisiveness and diffidence during the Balkan Wars, he gave proof of more resolve during the July Crisis.

[7]: 118 After having dispatched Count Hoyos on a mission to Berlin on 5 July to secure German support for Austria-Hungary's future actions, which resulted in the famous "blank cheque", he became the leading spokesman, together with the Chief of the Austro-Hungarian General Staff General Conrad von Hötzendorf, for war against Serbia during the meeting of the Imperial Crown Council on 7 July.

As the acceptance of all 10 demands listed in the ultimatum was required, the Austro-Hungarian government made a decision to enter a state of war with Serbia on 28 July, for which he was largely to blame.

When Rome presented the Ballhausplatz with demands for control over territories in southern Austria-Hungary, Berchtold demurred and refused to offer any Habsburg concessions, especially not in the Trentino.

Her maternal aunt, Countess Hanna Erdödy, was the wife of Count Béla Széchenyi von Sárvár-Felsövidék, a "personal friend" of King Edward VII.

[9] At the same time, his lack of self-confidence at the helm of Austro-Hungarian diplomacy made him susceptible to persuasion by his pro-war staff at the Ballhausplatz, on whose advice and opinions he was heavily dependent.