During discussion of the fight over Patroclus’s body in Iliad bk. 17, we said proper burial, to Homeric heroes, was a standard which helped the community function but was often broken in war. I think the fate of Hector’s body exemplifies this, both in its mistreatment and finally the circumstances of his burial, which involve Achilles finally giving up his wrath and being reconciled both to the Greeks and, however briefly, to the Trojans.
Achilles’s treatment of Hector’s body is the extreme of his wrath. Between mutilation and the lack of any burial – in contrast to Patroclus’s funeral games and elaborate pyre – Achilles treats the body the opposite of how one should.
But the moment when his wrath, subject of the whole epic, finally abates is when he sees Priam mourning and thinks of his own father: Achilles recognizes that the two are comparable, and that although Priam is his enemy in war they operate on some of the same principles. In allowing Priam to ransom Hector’s body and granting several days’ peace for Hector’s burial, Achilles treats Priam, in a way, as part of his community.
The cities at war and at peace on Achilles’s shield demonstrate the same thing: in the Iliad, war breaks social ties and ends in misery, whereas when the rules of the community are kept people can prosper and be happy. Hector’s burial is the final, and perhaps strongest, symbol of that sense of community in the Iliad.