Marx and Engels, March 1862 in the liberal Viennese paper Die Presse.
Now it may be argued that Marx was supporting the bourgeoisie at a time and in a situation of rising capitalism, in which the bourgeoisie was progressive. His articles in Die Presse seem to say little that is anti-capitalist and that may be because he needed the commissions. Yet he would have known that without the active support of Northern capital the war could not have been fought and won.
His seemed to see the defeat of slavery as a progressive cause, even though he would have known that in terms of state power this was a war between one exploiting class and another for the control of the entire nation state, its resources and its markets. The head of the executive committee of the bourgeoisie, Lincoln, he described positively as a man of average good will and praised his historic contribution.
The war was the first with really massive loss of life. It could well be presented as a war of two exploiting classes. Capitalism was consolidated on a unitary basis in the land later to become the superpower of the world. The working class were enlightened fodder for this enterprise. Surely the only revolutionary course would have been for the working class of each state to have united with the slaves and small farmers and had a revolution against their exploiting classes. A few proclamations from a centre of marxist leadership would have been sufficient for the revolution to start, providing that centre of marxist leadership was not occupied by a class traitor who propagated conciliation with the ruling class....
But for Marx the bungles and mistakes at the beginning of the war are associated with the difficulty of a more sophisticated democracy turning to war. Just as some of the most imperialist features of the present war, the massive bombing of Serbia, is also a feature of the difficulty of getting consensus among 19 democratic states for what would be more focussed and less destructive, a ground war limited as much as possible to Kosovo.
Now there must be a number of subscribers on this list who know Marx's writings on the American Civil War quite closely.
But as for Marx's would be followers, who are followers without reading Marx closely, they must be turning today in their graves - intellectual graves that is. Corporeally alive, but dialectically dead.