The main reason for the Persian War was because of King Darius of Persia wanted to expand his empire. The first time Persia invaded Greece, began in 492 BC. That’s when the war started. Late into the war, the Persians suffered a great defeat at the Battle of Salamis and the Battle of Plataea. Before that it seemed like the Persians would win the war, but Greece eventually won the war. Nobody knows what would have happened if the Persians won. The war is significant because the war ended with a Persian defeat in 490 BC.
The Peloponnesian War started with Sparta’s fear of Athens getting strong (because they were already a very strong nation) and overthrowing them. The war started in 431 BC beginning with Sparta starting a war with Athens. Sparta eventually won and then they became the strongest nation. Well, there were a few little wars between different nations competing for the strongest nation, but then they eventually became exhausted and they all gave up.