Boroević joined cadet school at the age of ten. After finishing grade school he moved to Kamenica and later Graz where he studied in military academies. He attended the Liebenau cadet school in 1875. After graduating from Military School he served as a Junior Officer in the army. He advanced quickly through the ranks. He was a corporal in 1872, and later on May 1, 1875 he became a lieutenant. He would also fight battles in Bosnia in 1878. He was awarded for his service in the capture of Sarajevo. Svetozar would eventually become a commander in the Croatian Home Guard. Before the First World War, he commanded the 42nd division of the Croatian Home Guard. In 1903 he was formally released from the Home Guard, already having been assigned to the Imperial & Royal Army in 1898. During war, the defensive troops were part of the Armed Forces commanded by the Supreme Army Command and could be used at the front. He distinguished himself in the Austro-Hungarian occupation of Bosnia and Herzegovina in 1878. Because of his service, he was awarded Military Merit Cross. Afterwards, he was promoted to the rank of Oberleutnant in 1880. From 1881 to 1883 he studied at the military academy in Vienna. Between 1887 and 1891 he underwent additional military training and worked as an instructor after that, and he would begin his teaching at the Theresian Military Academy. He would finish teaching there in 1891. Svetozar became a major in May 1892. In May 1895, he was promoted to the rank of Lieutenant Colonel. He would take control over a battalion of the 17th Infantry Regiment during the month of April in 1896. In November 1897 he was promoted to Colonel. Later he was appointed to chief of staff of the Seventh Corps of the Imperial & Royal Army in June 1898, where he remained until February 1904. In 1904, he was promoted Major General and took control of the 14th Infantry Brigade. In May 1905, he was created a Hungarian nobleman (since Croatia was one of the Lands of the Holy Hungarian Crown) with the attribute "von Bojna" by the Emperor & King. From 1907 to 1912 he commanded to VII Landwehr Division. On May 1, 1908, the monarch made him Field Marshal Lieutenant (Feldmarschallleutnant). In September 1909 he was put in charge of the VI Corps in Kosisce. He became the commander of the Sixth Corps of the I & R Army in April 1912 and on May 1, 1913 General of the Infantry.