Why was Fred Law Olmsted chosen to write the introduction of "An Englishman In Kansas" and why is it historical revelant?Where would I find this...

Thomas Gladstone was an eyewitness to sack of the city of
Lawrence by pro-slavery "border ruffians" in 1856 against a free-state stronghold
residing in the city. As the title of his work states, he was an Englishman visiting the
new state and not an American. While this may have made him an unbiased observer
(assuming there is such a thing), his European audience may have required a more
informative source who could describe the complicated political situation that was
occurring in Kansas.

In his biography of Frederick Law
Olmsted, Witold Rybczynski describes the man and his successful career before, during,
and subsequent to the Civil War. Olmsted's own work, The Cotton
Kingdom, surveyed in a series of articles, the economic and social conditions
of the South in regard to slavery. Olmsted was among those who first argued that the
institution was economically and morally depraved. This all making Frederick Law Olmsted
an excellent candidate for an introduction to Gladstone's published
articles.