Petrograd

Petrograd, Russia. The Imperial capital, Saint Petersburg was re-branded in 1914 to give it a less Germanic name. In 1917 the February and Great October revolutions started in the city. The football carried on despite the privations of the time, and did so during the Civil War and The Allied Intervention. 

Two dominant football clubs emerged in the city at this time, as the old guard of Saint Petersburg such as Sport and Unitas faded.

Kolomyagi

Kolomyagi was founded in 1904. The  club  started off as a small concern run by youths who raised money in the novel way of oragnizing dances. They then (pre revolution) went down the questionable route of trying to limit their membership to what they deemed to be the 'better' elements of society. The club played in blue and white. Kolomyagi  first participated in the Saint Petersburg championship in 1910, finishing second to Sport, to whom they also lost in the cup final. They reached the cup final again in 1912, losing to Unitas reserves. in 1914 they finished second in the championship (behind Sport) and in 1915 won their first major trophy, beating Unitas in the cup final.
Kolomyagi were Petrograd Champions in 1916 and came close to the double, losing 2-1 to Sport in the cup final (having scored 27 goals in the 2 previous rounds!)
In 1917 and 1918 Kolomyagi retained the championship. In 1919 the league was abandoned but the cup went ahead, Kolomyagi beating Mercur 7-1 in the final. 
In 1920 the championship was decided by a knockout tournament that Kolomyagi won by beating Mercur, a feat they repeated in the regular cup final- a quite remarkable game which went to extra time and produced a final score of 9-2.

Mercur

The other leading team in the city at this time was Mercur . Known as the merchant club- drawing their patrons and players from small businessmen and the working classes, they played in red and black stripes.  Mercur (Mercury) made their debut in 1906. After 2 poor seasons they dropped out of the league and reappeared in 1909 and were champions in 1911.

Indifferent seasons followed, though in 1914 Mercur reached the cup final, they were thrashed 8-2 by Sport.
They won the championship in 1915 and were runners up to Kolomyagi in 1916, 1917 and 1918. In 1917 and 1918 they won the cup, the latter being a 3-1 victory over Kolomyagi . As we have seen Kolomyagi enjoyed revenge in the next 2 seasons, thrashing Mercur 7-1 and 9-2 in successive cup finals and also beating them to the championship. 
Mercur enjoyed a further 2 championships (1921,1923)* in the years before Petrograd became Leningrad. 

* some sources have Mercur as 1922 champions, other as runners up and winners 'unknown'.