Prvog Ratnog Prvenstva Zagreba- 1918

A poster for 2 matches in a Zagreb championship tournament. The game  played on 19th May 1918 was between  Hrvatski akademski športski klub (HAŠK) and ŠK Zagreb. The following day FC Sparta Elektra would play HŠK Građanski.
Six clubs took part in this league and the final standings were as follows:

1. HAŠK
2. Građanski 
3. AŠK Croatia
4.ŠK Zagreb
5. Sparta Elektra 
6. HŠK Slavija Zagreb

Yugoslavia 1923

 Gradanski Zagreb

A Yugoslavian national championship was first contested in 1923, when the country was known as The Kingdom of Serbs, Croats and Slovenes. Up until the end of the war in 1918 the lands of Yugoslavia (what we now know as Serbia, Croatia, Bosnia Herzegovina, Slovenia , Montenegro and FYR Macedonia) were a part of the Austro-Hungarian Empire, and the clubs listed below were all formed during this period of Austo- Hungarian rule.
Six clubs participated in a knockout tournament to decide the inaugural national championship.

HSK Gradanski Zagreb
Founded in 1911, a multi sports club with an emphasis on Croatian identity. Gradanski won the Zagreb Regional Championship 6 times between 1919 and 1928.

 JSD Bačka
The oldest club in Yugoslavia, founded by members of the Croat/Bunjevac community in the city of  Subotica in 1901. They used to compete in the southern section of the Austro-Hungarian league. 

SASK  
 Sarajevo amaterski športski klub- Sarajevo is in modern day Bosnia Herzegovina.

Hajduk Split 
Founded in Prague by a group of students from Split in 1911. The clubs Croatian nationalist tendencies were reflected in the name- a Hajduk being a partisan fighter against firstly the Ottoman Turks and latterly the Austrian Empire.

SK Ilirija
Slovenian club from Ljubljana founded in 1911. Initially they played Zagreb based clubs because there were only 2 established clubs in Slovenia - Ilirija and Slovan. After 1918 football developed in Slovenia, and Ilirija won 12 Slovenian titles between 1920 and 1935.

SK Jugoslavija
 Serbian multi-sports club from Belgrade, originally founded as  SK Velika Srbija (Great Serbia) in 1913, 
changing its name to Jugoslavija in 1919.

First round: 
Jugoslavija 2-1 Backa
SASK 4-3 Hajduk
Gradanski 2-1 Ilirija

Semi finals: 
Jugoslavija 3-4 SASK
Gradanski bye

Final: Gradanski 1-1 SASK  
replay: Gradanski 4-2 SASK 

 Gradanski were coached by former Bolton Wanderers player Arthur Gaskell.
Dragan Jovanović of Jugoslavija was the competition's top scorer with 4 goals. In an 8 year career with the club he scored 331 goals in  252 matches.