I recently read Cedric J. Robinson's Black Marxism, the Making of the Black Radical Tradition, here's some quick notes.
Black Marxism falls into roughly two main sections. First is a history of capitalism, but it is one that begins with the crusades and shows their quite close connection (both ideological and chronological) to the Portuguese and Spanish colonisation of the Americas via the legend of Prester John (a legendary Christian kingdom believed to exist at various times in Central Asia then Ethiopia). Capitalism is then seen as both an outgrowth of, and the driving force behind, early colonisation and new world slavery via the middle passage.
Then through W. E. B. Du Bois, CLR James, and Richard Wright develops the thesis of a Black Radical Tradition, one that developed out of those those authors' experiences both with Marxism and black nationalism.
Robinson notes that all three authors found inspiration in Marx's work and the Marxist milieu of the inter-war years, but ran into limitations both with Marxist theory as it was in the '30s as well as the realities of the Trotskyist and Stalinist left at the time.
CLR James' Black Jacobins and Du Bois' Black Reconstruction are the two works which really dominate the book and rightfully so. Black Jacobins was on my reading list for about a decade before I actually got around to reading it, and I wish I'd read it much sooner. While it was early in James' political development (he was still a Trotskyist when he wrote it), you can see the tension between James' Leninist conception of revolutionary leadership embodied in Toussaint Louverture with the various tactical and ideological compromises Louverture makes against the self-organisation of the masses (between putting down maroon and plantation rebellions towards the start of the book and over-optimistic negotiations with France at the end). I have not yet read Black Reconstruction, but Black Marxism, like Black Jacobins is another spur to move it up the reading list.
Both the historical summary of the genesis of capitalism and the examination of James, Du Bois and Wright are valuable contributions to understanding theoretical and historical questions which have often not been given a proper treatment.
In the course of reading the book there were a few passages which I found lacking though, these shouldn't put you off reading it, but like Robinson's own introduction, they situatedthe book as part of a process of asking questions as much as answering them.
Firstly, Robinson quotes Perry Anderson's claim that "within the entire corpus of Western Marxism, there is not a single serious appraisal or sustained critique of the work of one major theorist by another, revealing close textual knowledge or minimal analytic care in its treatment". Anderson is simply wrong here, because in 1938 Anton Pannekoek wrote a significant critique of Lenin in 'Lenin as Philosopher', and Robinson doesn't correct this assessment. CLR James and Raya Dunayevska were corresponding with Pannekoek in the early 1950s while they were re-assessing Marx and the role of the revolutionary organisation, so they would likely have been aware of this work, even if Perry Anderson was not.
Robinson later quotes Du Bois:
"Where Marx had presumed that a bourgeois society established by a bourgeois revolution was a necessary condition of a conscious socialist movement. Lenin, in April of 1917, would declare that the process had been completed in Russia in less than three months".
While Marx did think that the advent of Capitalism in Western Europe was necessary for a conscious socialist movement there, he did not automatically apply this conclusion to the rest of the world. Marx's most concise statement of that argument is in his letter to the editor of Otecestvenniye Zapisky where he's clear Capital is a study of the development of Capitalism in Western Europe, not a recommendation that Capitalism be exported around the world as a precondition to socialism.
Du Bois, writing in the '30s, would not have had Marx's correspondence and later writing available to him. In fact Teodor Shanin's "Late Marx and the Russian Road" which collects some of Marx's drafts on Russia wasn't published until 1983, the same year as Black Marxism. Robinson however does not give Marx's writings on the American Civil War any treatment in the book (although again it's not clear whether Du Bois would have had access to them either, unlike much of Marx's writings at this point they're still not available online).
So with Black Marxism we have several 'Marxisms' simultaneously being responded to:
1. The work of Marx himself - which in the main was Eurocentric, but occasionally points towards an analysis of the colonies (his writings on the American Civil War and the Russian Mir). These other, incomplete, aspects of Marx are not adequately dealt with, a problem that is not at all unique to Robinson but is important in the context of the book's overall thesis.
2. 'Marxism' as the ideology of the third and fourth international, in which in the 1930s Lenin and Trotsky's interpretations dominated.
3. 'Marxists' as in the organised Marxist movement that Du Bois, James and Wright came into contact with via the American Communist Party and Trotskyist groups.
4. The Marxism that especially CLR James developed during his break with Trotskyism and Leninism (if not Lenin himself).
5. The other Marxisms, to which CLR James contributed, but which also existed prior to CLR James' engagement with them - i.e. Marx's own work, and the Dutch and German left (and the other targets of Lenin's Left Wing Communism and Infantile Disorder, which precipitated the organisational and theoretical break with the third international).
James' excavation of the Haitian Revolution uncovered an historical episode which Marx never dealt with, and thus it corrects a massive omission from Marx's work. However in general I think it's more useful to treat Marx's output as incomplete (while providing some tools to tackle subjects that Marx didn't deal with sufficiently), rather than seeing James' work as a break with it, since many others have made that similar break with Leninism while retaining what's useful from Marx.
It is this other Marxism where the treatment is lacking in Black Marxism. But it is in an engagement between Black Jacobins and the council communists that for example CLR James' landmark work Facing Reality from 1958 comes into play, and which allowed James to see the international significance of the 1956 Hungarian uprising. Is Robinson is dealing with James in the 1930s, before he reconnected with the dissident Marxist tradition in the late '40s and '50s (but was able to begin that break from his own historical investigation), or as a whole? Robinson also fails to mention Black women anarchists and Marxists such as Lucy Parsons or Claudia Jones, Parsons having produced a body of work and activism decades in advance of the people examined in the book.
The omission of Lucy Parsons also brings up an entirely separate discussion, which is the lack of mention of anarchism in the book - expected for something entitled 'Black Marxism' but maybe not for something attempting to wrestle with Marxism's limitations. However Robinson has apparently engaged with anarchism in his book 'Terms of Order', which i haven't read yet.