Xenophon's encomium on Agesilaus. Xenophon served in Agesilaus' army and was a personal friend of his.
Cornelius Nepos' Life of Agesilaus
Plutarch's Life of Agesilaus
Plutarch's comparison between Agesilaus and Pompey the Great
For general historical background down to the battle of Mantinea, see Xenophon's Hellenica: Books 3-7
Secondary Source:
Jona Lendering's page on Agesilaus is particularly good on Agesilaus' time in Asia.
Secondary Sources:
Jona Lendering's page on Agesilaus is particularly good on Agesilaus' time in Asia.
The above article is a combination of my Agesilaus II, King of Sparta Part 1/3, Agesilaus II, King of Sparta Part 2/3, and Agesilaus II, King of Sparta Part 3/3, which first appeared on Suite101.com on 9 August 2004, 23 August 2004, and 9 September 2004, respectively.

