People have written about wars for thousands of years. Herodotus's account of the Persian Wars is similar to journalism, though he did not himself participate in the events. Thucydides, who some years later wrote a history of the Peloponnesian War was a commander and an observer to the events he described. Memoirs of soldiers became an important source of military history when that specialty developed. War correspondents, as specialized journalists, began working after the printing of news for publication became commonplace.