Question

Old enough to fight, old enough to vote” became a major rallying cry for which amendment to the Constitution

Answer 1

Answer:

The 26th Amendment

Answer 2

Answer:

That would be the 26th Amendment. "The right of citizens of the United States, who are eighteen years of age or older, to vote shall not be denied or abriged by the United Statea or by any State on account on age." (rewritten in simpler terms)