" The Scramble for Africa", Thomas Pakenham. Not strictly a war book but plenty of war in it at every level, from the grand strategic, as European powers balanced their Treasury outlay with risk and reward; to the desperate survival against enemy and elements. It details the role of trade, alliances, host nation support and local resources. My favourite was the alliance of the British with the Gungo, a fierce tribe of cannibals who ate their way through the battlefield.
A good book, but I preferred Pakenham's "The Boer War", which is one of the best written history books that I have read.