During World War I, he joined the Royal Serbian Army and later visited Russia to gather recruits for the Balkan Front. After Serbia was overrun in a joint Austro-Hungarian, German and Bulgarian invasion in late 1915, Golubić retreated to the Greek island of Corfu alongside the rest of the Royal Serbian Army, where he began plotting to assassinate Kaiser Wilhelm with the apparent blessing of Dragutin Dimitrijević, the head of Serbian military intelligence. After travelling to France for the purpose of carrying out the plan, Golubić was arrested by the French authorities and deported to Corfu, where he was asked to testify against Dimitrijević, who had since been detained on charges of plotting against the Serbian crown prince, Alexander.