 Complete the following phrase:  Popović was born in 1881 in Sjenica, Kosovo Vilayet, Ottoman Empire present-day southwestern Serbia. His family fled from Ottoman rule and settled in Kragujevac, where he attended school. After graduating from the Military Academy in Belgrade in 1903 with the rank of infantry second lieutet, Vojin Popović chose to join the chetnik organisation in 1905, and in 1911 joined the secret organization Unification or Death Black Hand. He fought against the Ottomans in Macedonia and Old Serbia between 1905 and 1912 battles at Čelopek, Кumanovo, Prilep, Bitola, and the bank of the Vardar and against the Bulgarians on the river 