Conversation so far:
Where was Tom Tancredo born?
Tom Tancredo was born in Denver, Colorado.
Who are Tom Tancredo's parents?
Tom Tancredo was the son of Adeline and Gerald Tancredo.
What is special about Tom Tancredo's grand parents?
All four of Tom Tancredo's grandparents emigrated from Italy.
Where did Tom Tancredo go to college?
Tom Tancredo graduated from the University of Northern Colorado with a degree in political science.
What did Tom Tancredo do after college?
After graduating from the University of Northern Colorado Tom Tancredo became eligible to serve in Vietnam in June 1969.

Question: How long was he there?
Self-contained rewrite: How long was Tom Tancredo serving in Vietnam?