Answer:
According to the chart, the Greek writer who fought in a war and gave a firsthand account of what happened was: Thucydides.
Step-by-step explanation:
The chart we are analyzing here mentions different Greek writers and then offers some important pieces of information on each of them. For instance, when it talks of Homer, it mentions that he wrote the famous epics the "Iliad" and the "Odyssey".
When it talks of Thucydides, this is what it says:
Thucydides • historian who wrote about the Peloponnesian War, which he fought in
As a matter of fact, Thucydides's account of the war is highly valued for its literary and historic worth. The writer was an Athenian general in the war, fighting against the Peloponnesian League, from Sparta. He made sure to remain faithful to chronology in his account. He also used speeches to better elaborate on what took place, which is a practice long abandoned by historians, but common back then.