Even though he wrote for his book to last, that does not mean that he gave up all historical accuracy. Parts of the History of the Peloponnesian War are probably exaggerated to increase the entertainment value of the book as a whole but truth can be found and verified within its pages. This makes the book a work of history also.
The History of the Peloponnesian War can be verified with other documents and plays written about the same time. Each time part of the History of the Peloponnesian War is verified with another reliable source it increases its credibility of the History of the Peloponnesian War. Not all of the book can be verified or proven as an inaccuracy because of the limited amount of documentation that can be compared to the History of the Peloponnesian War.
Thucydides was writing about events that happened in his own time and could collect first hand accounts of battles that occurred and speeches that were given. Battles and military campaigns can be followed through written as well as through interviews with people making the historical fact in this aspect closer to what actually happened. Learning about the military actions is