Philip J. Haythornthwaite (born 1951) is an internationally respected and prolific author and historical consultant specializing in military history, uniforms and equipment. Whilst his main area of research is the Napoleonic Wars, his impressive list of publications covers a much wider range of periods from the English Civil War until WWI.
For the Wargamer or painter this is the only book you really need. A great little compact history. Then a meticulous discussion of all the uniforms of the war from the normal Dk. Blue/Lt Blue or Grey/Light blue to all the Zouaves(yep ALL the Zouave units) to the Garibaldi Guards' Sardinian inspired get up. Classic colour plates and then great notes that describe even more anomalies. A can't miss for the military enthusiast.