As a rule, you can count me among those purists who prefer to leave historic black and white films uncolorized. Just because we have the capability to dress Sam Spade in a powder blue suit doesn't mean the addition of color is an improvement for film noir classics like The Maltese Falcon that were all about light and shadow.
Parenthetically, I feel the same way about aging filmmakers who can't resist tinkering with the iconic films of their youth by adding digital effects and declaring these updates the definitive edition (yes George Lucas, I'm talking about you).
In the 1980s - the last analog decade - film colorization was a new and controversial practice largely driven by the demand for more television program content. The state of the art is extremely sophisticated today, however, and I can imagine situations where the addition of color could transform how we see historical periods that only a handful of the living can remember.
I wish I could say that World War I in Colour, the 2003 documentary narrated by Kenneth Branagh and produced for British television, achieves this transformation. It is a clever way to present historic footage that most modern viewers have never seen in a colorized palette that manages to still look archival. The grain of the film has been spared digital excision, though film speed appears to have been adjusted so marching soldiers and weaving vehicles don't lurch and scamper across the screen in unnatural movements. It is skillfully done, but the novelty of viewing 90 year old events in color instead of the original black and white wears thin and ultimately cannot carry the film. Though most of the film footage was new to me, the documentary is constrained by the images that were available and comes across as a very narrow survey of the causes and conditions of the Great War. Its most memorable parts, in fact, are the interviews with hundred-year-old veterans (all dead now, five years since the film was made). You hang on every word of these oldest of the old, whose eyes were seared by events of their youth that they cannot forget. For my money, what they add to our understanding of these vanished events is far more than the re-tinted film images they are meant to support.
Amazingly, color photography did exist during World War I, and various methods of producing photographic images in color have been around since at least the 1860s. Sergey Prokudin-Gorsky , for example, used a process that combined three monochrome images taken using different light filters to produce stunning color photographs of the Russian empire between 1902-1915.
The French also made advances in color photography during this period, with the glass plate Autochrome method of the Lumière brothers the color standard from 1907 until the advent of Kodachrome film in the 1930s. The French military made thousands of Autochrome images during WWI, a fine selection of which are viewable here and here.
This is history in living color, and all the more remarkable because it is not has we have re-imagined it but as it was actually recorded. Although I can still be seduced by the miracles of digital artistry, I find the accomplishments of these early 20th century color photographers far more impressive.