I think that it is perceived that the Homeric text encompasses the entire Trojan War. That is not the case. The length of the war was about a decade. Homer's work focuses on a small period in that war. The work focuses on "a few weeks in the final year of the war." Homer's work does make specific mention to previous events in the war and does place emphasis on how these weeks were so vital to comprehension of the war and its implications. When Homer opens with the invocation to the muse to sing of the wrath of Agamemnon, it is a reference to how this had been ongoing and the work takes this in the final year of the war with specific mention. The film approaches this a bit differently. Its depiction of the war does not specifically identify a time period of the war nor does it specifically identify how long its frame of reference is. One significant difference between both is that the film constructs its depiction of the Trojan War as one in which the start of the war through its end is shown. Homer's work does not do this, rightly suggesting that the war, itself, was in such magnitude that his work could only focus on a small portion of it. The film seems to suggest that it encompasses the entirety of it, from the abduction of Helen, to the need for Achilles, to Trojan victories and to their defeats. It is here where there is another significant difference in the depiction of the length of the war. Homer's work ends with the moral understanding of Achilles. Troy's falling and plunder is not shown. This is not the film's depiction of the war, which actually ends with the city of Troy sacked. In this, yet another difference in the length of the Trojan War is shown. Homer seems to be content with Achilles' moral revelation, one that is cemented knowing that his own death is inevitable, while the film ends with Odysseus overseeing the burning pyre of Achilles, noting a sense of conclusion in the film about the length and cost of the Trojan War.
Though the Trojan war is believed to be fought for ten,years the war continued without decisive results for nine years. Then an event occurred which seemed likely to be fatal to the cause of the Greeks, and that was a quarrel between Achilles and Agamemnon. It is at this point that the great poem of Homer, "The Iliad," begins. The Greeks, though unsuccessful against Troy, had taken the neighbouring and allied cities, and in the division of the spoil a female captive, by name Chryseis, daughter of Chryses, priest of Apollo, had fallen to the share of Agamemnon. Chryses came bearing the sacred emblems of his office, and begged the release of his daughter. Agamemnon refused. Thereupon Chryses implored Apollo to afflict the Greeks till they should be forced to yield their prey. Apollo granted the prayer of his priest, and sent pestilence into the Grecian camp. Then a council was called to deliberate how to allay the wrath of the gods and avert the plague. Achilles boldly charged their misfortunes upon Agamemnon as caused by his withholding Chryseis. Agamemnon, enraged, consented to relinquish his captive, but demanded that Achilles should yield to him in her stead, a maiden who had fallen to Achilles' share in the division of the spoil. Achilles submitted, but forthwith declared that he would take no further part in the war. He withdrew his forces from the general camp and openly avowed his intention of returning home to Greece.