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.

[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.

[5][11] Once war had started, Count Berchtold focused his efforts on the question of Italy's participation, the outcome of which would lead to his downfall.

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.