Jason - almost certainly it is my grandfather you are looking for - Dr Walter James Leckie. In 1870-72, he was a Colonel Surgeon in the Chilean army; later he was back in Chile, after serving as Surgeon Major in a field hospital during the Turco-Serbian war. Moved between Chile and Peru during the 1880s, serving as Medical Officer for various vice consulates.
I can tell you lots more about his life if you're interested - this should be enough to confirm that it is the right person!
His eldest son (my father) was called Walter Francis Leckie.
It turns pleasure into greater joy to hear that I have some black cousins.
I have family in Argentina, and if my finances were better, I'd return there myself, despite the terrible times they're going through. It is our kind of life.