Point Why do historians try to understand the historical context surrounding an
event when studying it?
A. It helps them make generalizations about the event for a wider
audience.
B. It ensures that they cannot be accused of plagiarizing their
sources.
C. It allows them to connect the event to broader historical trends.
D. It helps them refute claims that their interpretations of the event
are not valid.

"When a democracy is destroyed, it will not be from enemies from without, but rather because of enemies from within" means that Senator Joseph McCarthy was referring to the suspected infiltration of the Communists into the US Armed Forces.  

Why might Senator McCarthy have chosen to use this quote to support his claims?

He chose to use this quote to support his claims of  anticommunist hysteria of the Red Scare in America. He believed without substantial evidences that the US armed Forces has been infiltrated by the communist loyalist and if allowed unchecked could destroy their most cherished democracy. Unfortunately, all these came to ruins when he was shut down from his bogus fame when the soft spoke lawyer, with incisive wit and intelligence, Joseph Welch, special counsel for the U.S. Army, in a dramatic confrontation of the defense of the Armed forces in his celebrated statement “Until this moment, Senator, I think I never really gauged your cruelty or your recklessness.”