How significant were leftist radicals in black politics pre-civil rights movement? (ie pre-King)

Apologies to /u/comix_corp and /u/yolesaber for taking so long on this.

You are mostly correct that black radicalism tended toward either Garveyism (let's call it black nationalism, because then that incorporates Nation of Islam as well) or CPUSA-associated Marxism. There were also prominent black socialists like A. Phillip Randolph, who despised communism but was a huge workers' rights proponent. And still after those categories, you have Afro-Caribbean radicals who did not necessarily identify with the CPUSA or NOI, like Franz Fanon. But that's post-World War II when you see more pan-Africanism and anti-colonial movements. So let's stay to pre-World War II. And to 1930s, which is my area.

So how do we measure black radicals' influence in black communities? Is it enough to say that because writers like Hughes and Richard Wright were writing about radicals (mostly communists) that black radicals' presence was significant? Or, if black radicals weren't being elected to office or didn't have rallies with hundreds of thousands of people, they didn't really matter? It's such a hard question, and definitely something historians have struggled with. On the one hand, you don't want to undermine or belittle the efforts of black radicals. On the other hand, you don't want to make them out to be super popular people's representatives. For me as a historian, I look to see how and if black radicals' messages made it to the masses of black workers.

In Sojourning for Freedom: Black Women, American Communism, and the Making of Black Left Feminism, Erik McDuffie documents how during the Great Depression in Harlem, it was common to see people on step ladders and soapboxes talking about radical issues of unemployment, poverty, racism, etc. Mark Naison's Communists in Harlem during the Depression explores the many ways radicals drew blacks into the Party, from organizing social events to political rallies. Across the country, thousands of blacks participated in anti-eviction protests, often led by communists, to prevent poor black families from losing their homes. In urban areas, it was almost impossible for blacks to not know of the CPUSA. Does that mean every black person who stepped up on a ladder to rail against the government or went to a social dance sponsored by the CPUSA was a black radical? Certainly Party members like James Ford, Herbert Newton, Audley Moore, James Patterson, Louise Thompson, and so forth were black radicals.

In his foundational work,Black Marxism: The Making of the Black Radical Tradition, Robinson defines black radicalism as a “negation of Western civilization,” and a “specifically African response” to oppression wrought by European development. It is historically constituted and constructed, and always changing. It can be found in the daily practices of a single working mother who only shops in black-owned businesses, or in the revolutionary writings of Langston Hughes, WEB DuBois, or Richard Wright. Because discussions about radicalism were so pervasive in 1930s working class neighborhoods (thanks to the efforts of socialists and unionists like Randolph, communists, or black nationalist groups like NOI or UNIA), black radicalism was everywhere. In 1933, Carrie Smith, who had been working at nut-picking factory in St. Louis for over a decade, led her fellow African American workers out of the factory in a strike because they were being paid less than white women. In Cleveland, Maggie Jones's son was no longer offered free lunch at school, so she went to her local Unemployed Council and had them petition the school. In Detroit, Mattie Woodson held union meetings for the automobile industry in her own home. Were these women black radicals? They actively protested and organized against systems of racial and class oppression, recognizing their needs as working-class blacks were put last, in order to gain immediate needs.

So, back to your question: "Were the leftist radicals ever prominent in the black community?" Of course we'll never be able to say that this percentage of African Americans identified as black radicals, but if you interrogate what it means to be a black radical during the 1930s, you see many blacks working with radicals, under radical ideology, and for radical ends on a daily basis. So...were they radicals? In my opinion as a historian, yes. They fought race, class, and gender oppression during a time when no one else was. And there were a variety of levels of activism; from the everyday to the extraordinary, and that helps define radicalism.

For your second question, mostly no. Blacks who identified as radicals or aligned themselves with radicals generally went along with the central Party line, which during the early 1930s was the Comintern's Third Period, and after 1935, the Popular Front Era. There were certainly ideological differences, especially when it came to the "Negro Question." (see Harry Haywood's Black Bolshevik: Autobiography of an Afro-American Communist for more on this). One stark example of ideological differences was Lovett Fort-Whiteman, often considered to be the first African American in the CPUSA (see Glenda Gilmore's Defying Dixie: The Radical Roots of Civil Rights, 1919-1950 for more on Fort-Whiteman). After expressing "counterrevolutionary" ideas, Fort-Whiteman was sentence to a gulag in 1937, where he died. Then there were blacks like Otto Huiswood, who, during the Lovestonian-divided, firmly sided with the Comintern. Then there were women like Carrie Smith who joined the Party but still went to church every Sunday and led the picket lines in prayer every morning. There's really no words to describe what kind of Marxist she was.

In sum, it depends on what you mean by "black radical." Going back to Robinson, I think the more inclusive we are with the term, the more we can truly see the revolutionary of actions by people of African descent. I hope this helps. I highly suggest you read Naison's book, if you're truly interested in this material.

EDIT: I don't know why the font changed. Sorry.

ALSO: I can't believe I forgot Scottsboro, which stirred up black communities around the nation. In short, Scottsboro refers to nine young African American men who were arrested and falsely accused of rape near Scottsboro, Alabama. Eight received the death penalty after a farce of a trial. The International Labor Defense, affiliated with the communist party, but not officially communist) took control of their case and made it an international cause. Thousands of blacks participated in protests, meetings, and gave money to support their cause. After 1935, the ILD joined forces with the NAACP and other moderate organizations, thereby drawing in even more support.