In 1897, he was born to Josef Aehrenthal and Maria Aehrenthal. In 1905, he met a boy named a Franz Murnau and they became friends. In 1908, when Austria-Hungary annexes Bosnia and Herzegovina, Josef then dreams of being a soldier. So he waits until he is 17 years old. In 1914, he and Murnau tried to join the Austro-Hungarian army. Both of them were accepted and were in the same division.