Final answer:
Thurgood Marshall served as the general counsel for the NAACP Legal Defense Fund and was instrumental in landmark civil rights cases, including Brown v. Board of Education.
Step-by-step explanation:
The general counsel for the NAACP Legal Defense Fund during the period leading up to and including the Brown v. Board of Education case was Thurgood Marshall. Marshall, who later became the first African American justice on the U.S. Supreme Court, played a significant role in advancing the cause of civil rights. He was at the forefront of legal strategies that challenged racial segregation and discrimination, representing the NAACP in landmark cases that sought to dismantle the legal basis for segregation in American society, notably winning the Brown v. Board of Education case that declared state laws establishing separate public schools for black and white students unconstitutional.