Thurgood Marshall's early legal battles laid the groundwork for civil rights in the U.S. as he challenged racial segregation and discrimination in landmark cases. His involvement in the NAACP and the significant victory in Brown v. Board of Education helped dismantle the Jim Crow laws and shaped the framework for future civil rights legislation. These victories not only advanced the legal rights of African Americans but also inspired a generation of activists, strengthening the civil rights movement and promoting the idea of equality under the law for all citizens.