Following Austria-Hungary's annexation of Bosnia and Herzegovina in October 1908, Nušić led a series of anti-Habsburg demonstrations in Belgrade. He climbed a balcony at the National Theatre, railed against the "plunder" of Serbian lands by Austria-Hungary, and demanded immediate military action. He subsequently rode his horse into the Ministry of Foreign Affairs, to the consternation of Prime Minister Nikola Pašić. The popularity of Nušić's works, as well as those of fellow dramatist Petar Kočić, increased dramatically following the annexation. In 1912, Nušić returned to Bitola as a civil servant. Macedonia was captured and annexed by Serbia following the First Balkan War, and in February 1913, Nušić was appointed prefect of Bitola. He was quickly forced to resign after consistently failing to adhere to the demands of the Black Hand and the ultra-nationalist guerilla bands that formed the backbone of the Royal Serbian Army's occupation force. Despite this, he remained in Skopje, and helped establish the city's first theatre in 1913. The outbreak of World War I brought further personal tragedies Nušić's way; his son Strahinja was killed on the frontline while serving in the Serbian Army. Nušić lived in Skopje until November 1915, when Austria-Hungary, Germany and Bulgaria successfully invaded and occupied Serbia. He took part in the Serbian army's retreat through Albania between November 1915 and February 1916. He lived in Italy, Switzerland and France until the end of the war.