Simplify the following text for a Grade 12 native English-speaking person.
Original: The Plague of Athens was a devastating epidemic which hit the city-state of Athens in ancient Greece during the second year of the Peloponnesian War ( 430 BC ) , when an Athenian victory still seemed within reach .
Simplified: The Plague of Athens was an epidemic which hit the city-state of Athens in ancient Greece during the second year of the Peloponnesian War ( 430 BC ) , when an Athenian victory still seemed possible .