What was the name given to the idea that if vietnam fell to communism, the rest of southeast asia
would become communist?

This was known as the Domino Theory.

The term was coined during the presidency of  Truman and his Truman Doctrine.

The Truman Doctrine during the Cold War focused on a policy of containment of Soviet Union. The Domino thoery believed that if one country fell under the influence of the Soviet Union, it will pave the way for others.

The Truman Doctrine was publicised ont he 12th of march, 1947 and ushered in an Era of extreme competition between the United States and Soviet Union.

Many Scholars attribute the Vietnam War to the United States policy of containment.

accomplishment : zachary taylor’s was a national war hero in his battle in an mexican war

explanation:

he was known as a national war hero for his battles in the mexican war, taylor was elected as the 12th president of the united states in 1849. he led the nation during its debates on slavery and southern secession. after serving only 16 months in office, taylor died from cholera morbus on july 9,