Sosnowiec, which was soon renamed into RKU Sosnowiec. Its chairman was Major Marian Rodza, military commandant of the city. First postwar manager was Józef Słonecki, who in the 1920s was a player of Pogoń Lwów. In 1946, RKU qualified to the Ekstraklasa playoffs. In the 1/8 finals, it beat Gedania Gdańsk 6–2, to lose 0–4 to AKS Chorzów in the quarterfinals. During the game, which took place in Chorzów, clashes erupted between supporters of both teams, and the game was cancelled. In 1947, RKU was in Group Two of the Ekstraklasa qualifiers. This group was won by AKS Chorzów, RKU was the fourth team, behind AKS, Cracovia and Rymer Radlin. In 1949, after changing its name into Stal Sosnowiec, the team qualified to the Second Division, remaining there until 1954, when it was finally promoted to the Ekstraklasa. In the 1955 Ekstraklasa, Stal Sosnowiec was a sensation, as it was the runner up, finishing the season in the second spot, only behind CWKS Warsaw. Stal had 27 points, while CWKS had only one point more. In 1956, Stal was the 10th team (out of 12), in 1957, 7th, and was relegated in 1958, to return to the Ekstraklasa in 1960. Stal remained in the top league until 1974, finishing as the runners-up thrice (1964, 1967, 1972). Meanwhile, in 1962, Stal changed name into GKS Zagłębie . In the mid-1960s, the team from Sosnowiec was among the best Polish sides, as it once won Polish silver, three times bronze, and two times the Polish Cup: in 1962, after beating 2-1 Górnik Zabrze, and in 1963, after beating 2–0 Ruch Chorzów. In 1964, Józef Gałeczka was Ekstraklasa's top scorer. Among other notable players of that time was Andrzej Jarosik, twice Polish top scorer (1970, 1971). Furthermore, Włodzimierz Mazur was the top scorer in 1977. In 1977 and 1978, Zagłębie twice won the Polish Cup, and in 1979, Wojciech Rudy was named Best Polish Player of the Year. In 1986, Zagłębie, after 11 years, was relegated to the Second Division. It remained there until June 1989, when Zagłębie returned to the Ekstraklasa. Among its top players were Marek Bęben, Ryszard Czerwiec and Maciej Mizia. After promotion, the games of Zagłębie were attended by thousands of people, with the record, 28,000, watching the match against Górnik Zabrze. After the 1991 season, Zagłębie avoided relegation in the playoffs, in which it beat Jagiellonia Białystok 0–2,