 Complete the following phrase:  Upon his return to Serbia, his whirlwind military career began: from a sergeant in an artillery regiment, he was promoted to head of the General Staff Section and Chief of the Ministry of the Military by 1910. In the same year, he was appointed a military envoy to St. Petersburg, where he remained until the beginning of the Second Balkan War. After returning to Serbia, he took command of the Drina Division, which distinguished itself in the 