CSKA Sofia

1923–1948

In November 1923, three Sofia-based football clubs (Officers' Sports Club, Athletic Sofia, and Slava Sofia) merged to form AS-23, short for Officers' Sports Club Athletic Slava 1923, under the patronage of the Ministry of War, which provided the equipment.

In 1931, AS-23 won their first Bulgarian championship and The Tsar's Cup, followed by another Tsar's Cup in 1941. The club's stadium (completed in 1938) was named Athletic Park and was situated where the Bulgarian Army Stadium now resides.

On 9 November 1944, with the support of Mihail Mihaylov, an accountant at the Ministry of War and a patron of Shipka Sofia, a unifying agreement was signed, merging AS-23, Shipka, and Spartak (Poduene) to form Chavdar Sofia. Gen. Vladimir Stoychev from AS-23, who at the time was fighting on the front in World War II, was appointed (by telegram) as the new club's chairman. Lawyer Ivan Bashev, a future Bulgarian foreign minister, was appointed club secretary and the person in charge of football.

1948–1962

With the help of Mihail Mihaylov again, in February 1948, Chavdar became the departmental club of the Central House of the Troops ("Centralnia Dom na Voiskata") and took on the name of CDV. Looking for ways to stop the club's decline, CDV's administrators sought to merge it with another club. In May 1948, an agreement was reached between CDV and Septemvri Sofia (which had already earned a place in the play-offs) for uniting the clubs under the name "Septemvri pri CDV" (Septemvri at CDV). The contract was signed on 5 May 1948, which is officially considered the club's date of foundation.

The club's played its first official match on 19 May 1948 against Slavia Sofia at Yunak Stadium, a 1–1 draw. Septemvri pri CDV eliminated Aprilov (Gabrovo) and Spartak Varna en route to the final, where it faced Levski Sofia, losing 1–2 in the first leg. The decisive second match occurred on 9 September 1948. Septemvri pri CDV's lineup consisted of: Stefan Gerenski, Borislav Futekov, Manol Manolov, Dimitar Cvetkov, Nikola Aleksiev, Nako Chakmakov (captain), Dimitar Milanov, Stoyne Minev, Stefan Bozhkov, Nikola Bozhilov and Kiril Bogdanov. The score was 3–3 on aggregate, as Septemvri pri CDV led 2–1 near the end of regulation time, when a last-minute goal by Nako Chakmakov gave the club its first ever title.

In 1950, the word "Narodna" ("Peoples" in English) was added to the name of the Central House of the Troops, changing it to Central House of the People's Troops ("Centralen Dom na Narodnata Voiska" in English), or C.D.N.V., effectively changing the club's name. The following two years, C.D.N.V. won two consecutive titles. In 1951, the club clinched their first double. In 1953, the club was again renamed by the authorities, this time to Otbor na Sofiyskiya Garnizon ("Team of the Sofia Garrison"), and most of the key players were illegally transferred out. The title was lost.

The following year, the club was renamed CDNA (Central House of the People's Army), and the years between 1954 and 1962 marked one of the most successful periods for the Reds, who won nine consecutive titles (an unprecedented achievement in Bulgarian football at the time and a record the club held for 60 years) and, in 1956, took part in the second installment of the newly created European Cup competition, reaching the quarter-finals.

1960s

In 1962, CDNA was merged with DSO Cherveno Zname to form CSKA Cherveno Zname ("CSKA Red Flag"). The Central House of the People's Troops ceased its affiliation with the club, which was taken over by the Ministry of People's Defense. CSKA finished third after Spartak Plovdiv and Botev Plovdiv in the 1962–63 season. The following season, CSKA had its worst performance in the Bulgarian championship to date, finishing 11th in the final table, only three points from relegation. This led to the sacking of legendary coach Krum Milev after 16 years at the helm.

CSKA did not recapture the title until 1966. However, during the 1966–67 season, CSKA recorded its first major international achievement, reaching the semi-finals of the European Cup for the first time, where they faced Italian giants Inter. After two hard-fought 1–1 draws, a third decisive match was played, which CSKA lost 0–1.

The next two seasons were unmemorable for the Army Men, finishing in fifth and second place respectively. In 1968, CSKA underwent another merger, joining with Septemvri Sofia and taking on the name of CSKA Septemvriysko Zname ("CSKA September Flag"). The club clinched the title in 1969 with the help of recent acquisition Petar Zhekov, who would go on to become the top Bulgarian goalscorer of all time, a record Zhekov held for 52 years until he was surpassed by Martin Kamburov in 2021.

1970s

The 1970s are widely considered the period when CSKA made its name on the European stage. The club began the decade modestly, claiming second place domestically and reaching the round of 16 in 1970–71 European Cup Winners' Cup, where they fell to English side Chelsea 0–2 on aggregate. However, from 1971 to 1973, CSKA won three consecutive titles and delivered one of the biggest surprises in European football when it eliminated reigning European champion Ajax – considered the finest team of all time – 2–1 on aggregate in the 1973–74 European Cup.

They then faced German champions Bayern Munich in the quarter-finals. After losing 1–4 in the first leg in Munich, CSKA bowed out of the competition following a 2–1 win at home. Between 1975 and 1979, the club won two more domestic titles.

1980s

The 1980–81 season was again a memorable one for CSKA Sofia, winning the Bulgarian title once more and twice beating European champion Nottingham Forest, both times with 1–0 scorelines, before being stopped by the future European champions Liverpool with a 6–1 defeat on aggregate in the quarter-finals of the European Cup.