Subotica in 1898, the Szabadkai Sport Egylet (Sport Club Szabad), among the then fans better known simply as "Sport", within which was formed a football section in 1898 on the initiative of player and enthusiast Zoltán Wagner. Another club was founded in Subotica on May 3, 1901, the Sports Athletic Club Bačka. More than two years later, on 14 September 1903, the football club Šumadija was founded in Kragujevac. The Subotica clubs were older, but at the time of the foundation of Sport and Bačka, the city of Subotica was part of the Austro-Hungarian Empire, while Kragujevac was on the territory of the then kingdom of Serbia. Being still active, Bačka is the oldest club in nowadays Serbia. Just following the foundation of Šumadija, Soko was founded in Belgrade, and thus became the first football club from the capital city. Since then several other clubs were formed such as Srpski mač in 1906, BSK in 1911 and SK Velika Srbija (later renamed to SK Jugoslavija) in 1913. In spring 1914, the Serbian Olympic Committee organised the first ever trophy to be played among the best football clubs of the Kingdom of Serbia. It was played in a single-round robin system, and in the final held in Belgrade it was won by Velika Srbija. This seemed to be a promising start of an organised football tournament to be held regularly, however later that same year the Austro-Hungarian Empire declared war against Serbia in what will be the beginning of the First World War and the halt of all recreational and sports activities in Serbia. Kingdom of Yugoslavia At the end of the First World War the boundaries in the region were changed and the Serbian state was part of the Kingdom of Serbs, Croats and Slovenes, later in 1929 renamed into Kingdom of Yugoslavia. The Yugoslav Football Association (Jugoslovenski nogometni savez) was founded at a meeting in Zagreb, on 18 April 1919. The founding assembly was presided Danilo Stojanović, popularly known as Čika Dača, important because he was the founder of several football clubs such as Šumadija, BSK and others. In 1919 the Belgrade Football Subassociation formed the first league tournament that started being held regularly since its inaugural season in 1919–20. The first Yugoslav state championship was launched in 1923. The championships were played until 1940, and in this period the best Serbian clubs won seven state championship titles: BSK