In Order:
D - World War II Ends
C - President Truman ends segregation in the armed forces.
B - U.S. Supreme Court rules in Brown v. Board of Education.
A - The Civil Rights Act passes.
Step-by-step explanation:
World War II ended in 1945 (or 1946 is you count the surrender of Japan).
President Truman ended segregation in the Armed Forces on 1948
Brown v. Board of Education of Topeka was on 1954 (before the Little Rock Nine)
Civil Right Act passes 1964 (After The March on Washington)