Before 431 he took no prominent part in Athenian politics.
He was in his twenties when the Peloponnesian War occurred, and was in active service at the time.
In 427 he caught the plague and recovered.
In 424 (his mid thirties) he was appointed strategos.
He failed to save Amphipolis from Brasidas during the War in 424 (see Battle of Amphipolis). He was exiled for seven years.
From 423 to 404 he lived in Thrace. During this time he travelled the Peloponnese, using his status as an exile from Athens to assimilate in to the Peloponnesian allies. He may have travelled to Sicily for the Sicilian Campaign, as there are excellent examples of local knowledge. During this period of time he conducted important research.
He returned to Athens in 404, but was only there for a short time before he returned to Thrace to work on his book. His book contains the description of the war up until the year 411.
The sudden end of his work suggests that he may have died a sudden death, and there is strong evidence to suggest he did not live longer than 399.
His remains were returned to Athens and were laid in Cimon's family vault.
His character was said to be dry, humourless and pessimistic. Thucydides admired Pericles and approved of his power over the people, despite his usual disgust for demagogues. Thucydides was not completely in favour of democracy, but thought that it was ok when in the hands of a good leader.
Thucydides would have been schooled by Sophists. They were the teachers in Athens but today would be considered more like Philosophers and Astronomers Thucydides would have been taught by them not to accept things at face value, to question things. They would have taught Thucydides the mechanics of his writing, and they endowed him with his skills to assess the truth. Unfortunately, Thucydides is completely unaware of the workings of Economics he was not taught them, and did not understand them so they are omitted from his work.
Thucydides is generally regarded as one of the first true historians, along with Herodotus (who wrote "The Histories" about a generation prior). However, Thucydides, unlike Herodotus (who is often called "the father of history"), did not include references to myths and the gods in his writing. He vigorously consulted written documents and interviewed participants in the events that he records.
Even for someone disputing his status as the first historian; no-one would deny his status as the first and last historian of naked real-politik. Actors on the world stage who had read his work would all have been put on notice that someone would be scrutinizing their actions with a reporters dispassion, rather than the mythmakers and poets compassion and thus concsiously or unconcsiously participating in the writing of it. His Melian dialogue is a lesson to both reporters and to those who believe ones leaders are always acting with perfect integrity on the world stage.Timeline of his life
Who was Thucydides