Who were the most successful football teams of the 1910s?

The 1910s marked the early days of professional football in many countries, and several teams rose to prominence during this period. In England, the dominant teams of the decade were Everton, Sunderland, and Blackburn Rovers. Everton won the Football League First Division title twice in the decade, in the 1914-15 and 1919-20 seasons. Sunderland also won the title twice, in the 1912-13 and 1914-15 seasons, while Blackburn Rovers won it once, in the 1911-12 season.

In Scotland, Rangers and Celtic continued their fierce rivalry throughout the decade, with Rangers winning the Scottish Football League title four times and Celtic winning it twice. In Europe, Scandinavian teams such as BK Frem, FC Copenhagen, and AIK Fotboll enjoyed success in their respective leagues.

It's important to note that football was not as organized and structured as it is today, and there were significant differences in the rules and regulations across different leagues and countries. However, the teams mentioned above are widely considered to be among the most successful of the 1910s.