According to www.ShilohPostcards.com, "the first
postal card was suggested by Dr. Emanuel Herrmann, in
1869, and was accepted by the Hungarian government in
the same year. The first regularly printed card appeared
in 1870, a historical card, produced in connection with
the Franco-German War. The first advertising card appeared
in 1872 in Great Britain. The first German card appeared
in 1874. Cards showing the Eiffel Tower in 1889 &
1890 gave impetus to the postcard heyday a decade later.
A Heligoland card of 1889 is considered the first multi-colored
card ever printed."