The Vietcong set up checkpoints around the nation, so that would've definitely been a literal and figurative roadblock to any refugees. Hope this helped.
The correct answer is Beowulf/the dragon.
Beowulf is the main character in the epic poem "Beowulf," which means that he is the protagonist. Antagonist is a bad character, who is usually the protagonist's worst enemy. In the beginning of the poem, the antagonist was Grendel, but at the end, it was the dragon.