Ken Burns' genius was to bring those photographs together in almost a cinematic way to make the war, and the people involved, more real.
Scorcese's movie, although it takes place during the Civil War, is really not about that War at all. It is more about the earlier- and later-arrived Irishmen, and how they inculcated themselves into a hierarchical society in New York City. The first great Irish immigration wave was during the building of the Erie Canal in the 1820's. Most of the Irishmen who were already there and under the leadership of Bill "The Butcher" Cutting were part of the 1840's Irish potato famine crowd-a rough time for Irishmen to enter the U.S. as there were few jobs after the depression of 1848, and an actively hostile reception both from established Irishmen and the WASP's who controlled the political machinery of New York.
Since Scorcese's movie focuses on the tension between "old" Irish and newly-arrived Irishmen, led by Leonardo DiCaprio's Amsterdam Vallon, the Draft Riots of 1863 are an inconvenient truth whose underlying issues are ignored in the movie. Without a knowledge of the actual historical events of the time, and only viewing the movie, one might be led to believe that the riots were about old versus new immigrants, contained by a WASP police force under the leadership of Boss Tweed. The reality was quite different: General USS Grant and President Lincoln needed hundreds of thousands of troops in order to maintain a numerical superiority over the South, and they regarded the Irish immigrants of New York as a ready source of human capital for the war. Those in New York who had few roots in the American culture did not want to throw themselves in front of Gattling guns and cannons on battlefields like Gettysburg and Appomatox.
So how was the "truth" injured by Scorcese's movie One might argue that he should have chosen a different era, perhaps before the Civil War and not related to the Draft Riots, to exploit the tension between old and new Irish immigrants. While the plot could have been truer to historical fact, the tension of the plot might not be there. Scorcese needed to have a dramatic tension, a build-up, in his movie, leading to an apocalyptic riot where all of New York was burning. The 1863 riots provided that dramatic backdrop, one which would not have been available in the past.
As contrasted to other movies covering the same time period, "Gangs of New York" offers three original contributions: (1) it features a part of the population during the Civil War that was not at the front lines, (2) it gives a young person's perspective, as compared to the older, in-charge leaders such as Boss Tweed and Lincoln, and (3) it is a group pastiche, rather than a concentration on one leader, such as is found in "Glory."
Perhaps the best comparison to "Gangs of New York" is the epic "Birth of a Nation" by D.W. Griffiths (1915). Like "Gangs," "Nation" was an ensemble piece, one which explored not just the leaders of movements, but the underlying motivations behind the resentments and conflicts-in this case, between blacks and whites at the time of the Civil War and just after. Of course,