Aristides acts as a great introduction to the wars that made Athens great, the defensive wars against the Persian invaders, occurring between 490 and 479 BC. Plutarch admired Aristides immensely, so he serves as a great introduction to the standards Plutarch holds up for the other leaders he studies.
The outline of his life pretty much follows the important events of the Persian Wars:
I also link the important people to their places:
Translation
The most modern translation available, while still being in the public domain.