I finished Gates of Fire by Steven Pressfield a few days ago. It tells the story of the Spartans who led the small force at Thermopylae when they held off the full Persian army for 3 days in 480 BC. According to Herodotus, the Persian forces numbered 2 million while the defenders numbered only a few thousand, with just 300 Spartans (including their king, Leonidas).

The book takes the form of the recollections of a survivor told to the staff of Xerxes, the Persian emperor and covers the period from the survivors youth to after the Persian's naval defeat at Salamis. It does a good job of creating some interesting characters and a portrait of Greece at the time including Sparta, one of the oddest societies in history.

Amazon link: Gates of Fire