Homer's Iliad opens as Greek narratives frequently do with an invocation of the muses and a statement of purpose. "Rage-Goddess, sing the rage of Peleus" son Achilles" (b.1, l.1). Many people reading this line might assume, with apparently good reason, that the Iliad is a tale of Achilles. The only problem with this conjecture is that the greater part of the text is not about Achilles.
A large portion of the narrative is based on events surrounding Achilles, and more particularly his rage, though his name is rarely mentioned in books II through VII. Yet, we cannot ignore the clear implication of the first line. Without further analysis we are caught between two different views of the primary subject of the book: i) that Achilles is the center of the story and that the rest of the text is simply filler and background, or ii) that the Iliad is an account of the final months of a great and legendary war, in which Achilles is a major figure, but hardly at the core of the plot or purpose.
If the text of the Iliad were simply the story of Achilles and his actions in Troy, then an extremely large portion of the book would have to be labeled filler. The aristeias of Patroclus and Diomedes could be labeled as background, and they do function well as such. Diomedes supports the Achaeans in Achilles" absence and offers an example of a standard hero to compare to Achilles. Patroclus" shining moment and tumultuous fall directly lead up to Achilles re-entrance into the fighting. It seems a little strange for the first two thirds of a story to be nothing more than staging for the ultimate portion; however, it is conceivable that this is simply the nature of the Homeric style.
These two tales of divine inspiration are not the only sections of the Iliad from which Achilles is absent. There are hundreds of side descriptions of conversations, arguments, battles, and the inevitable deaths of multitudes of Achaeans and Trojans.