The club named after a horse...

Club Atlético Porteño (Buenos Aires) was originally formed in July 1895 as Club Atlético Capital. The founders were Irish immigrants . They gambled the club kitty om a horse called Porteño. The horse won, and the club flourished, so they changed the name of the club to that of the horse. 
They rose to the Primera División in 1907 and remained there until until 1928 . When Argentinian football was professionalised in 1931 the football club dropped out of the league. Porteño is now predominantly a Rugby Union club.
Porteño won the Federación Argentina de Football Primera División in 1912 and 1914 and the Copa de Competencia Jockey Club in 1915 and 1918.
Porteño also featured in 2 annual interleague contests , the Copa Rosario (Culaciatti) and Copa Mariano Reyna, in which they represented the Asocación Argentina de Football against Liga Rosarina (invaribaly Rosario),
The team photo comes from the 1919 Copa Rosario final, which Porteño won 1-0. 
The stripes were Royal blue and white.