Final answer:
The reference to Governor Faubus, Jackie Robinson, and Eisenhower's actions emphasizes the critical role of presidential intervention in civil rights and enforces the authority of federal law over state opposition.
Step-by-step explanation:
The mention of Governor Faubus, Jackie Robinson, and the letter to President Eisenhower strengthens the main argument of the letter by illustrating historical instances where Presidents took decisive actions in enforcing federal law over state opposition regarding civil rights.
Specifically, it showcases President Eisenhower's commitment to uphold the Supreme Court's order for integration, by nationalizing the Arkansas National Guard and dispatching troops to enforce desegregation in Little Rock, Arkansas.
This reference to decisive executive action serves to underscore the importance of presidential intervention in civil rights matters and puts into context the achievements of the civil rights movement.