Answered

which war advertisement uses the Beautiful People propaganda technique to convince people to join the Army

Verified Answer :

They used celebrities to endorse their propaganda to the
public.  If people see that high-profile
celebrities and officials support this campaign it can convince them to join
and support this as well.  Even today,
when celebrities voice their support on issues it gives that propaganda a huge
support.

Answer:

This World War II advertisement shows the famous boxer Joe Louis with the caption "We're going to do our part . . . ."

Explanation: