He was apparently a war correspondent. I'd expect that he was an imperialist in much the same way as his contemporary Rudyard Kipling.

This from his publisher's page: " Henty's stories revolve around a fictional boy hero during fascinating periods of history. His heroes are diligent, courageous, intelligent and dedicated to their country and cause in the face, at times, of great peril. His histories, particularly battle accounts, have been recognized by historian scholars for their accuracy. In fact, the only criticism Henty faced by the liberals of his day was that his heroes were "too Christian." There is nothing dry in Mr. Henty's stories and thus he removes the drudgery and laborious task often associated with the study of history."