King Priam was premiered 50 years ago this month in Coventry, to mark the consecration of the city's new cathedral. The following night, Benjamin Britten's War Requiem received its first performance. Both works spoke pointedly about the experience of war; the cathedral had been built alongside the ruins of its medieval predecessor, bombed to oblivion on the night of 16 November 1940. Of the two works, it is the Britten – with its weaving of the liturgy of the requiem mass with Wilfred Owen's trench-worn verse – that has had the most flourishing afterlife. Sir Michael Tippett's King Priam, with its libretto based on Homer's Iliad – is rarely performed and little known.

That may be about to change. King Priam is to receive a concert performance at the Brighton festival this weekend. Meanwhile, English Touring Opera is advancing plans to stage the work in the 2014-15 season, its first UK production since English National Opera's in 1995. For the Brighton festival, the work fits into a strand devised by guest artistic director Vanessa Redgrave, which takes the Iliad both as the foundational work of literature of the western world and as a war poem that still speaks to us of the trauma of conflict.

Tippett's own libretto for his opera fits into a tradition, nearly 3,000 years old, of responding to, arguing with, and rewriting Homer, a process that began with the dramatist Aeschylus, and whose latest iteration is Alice Oswald's 2011 poem Memorial, in which the epic's flesh is removed, leaving behind the lines that record its heroes' deaths: it is a kind of a verse hecatomb, death piled on death piled on death. With the open-ended quality of the Iliad's poetics comes the possibility of countless interpretations, infinite vistas that slant out from its humane, grand, ringing lines.

For each generation of readers, the Iliad seems to reflect back their own experience. Alexander the Great, no peacenik, slept with a copy under his pillow, according to tradition. The Iliad we read today – informed by the doubts and terrors of modern warfare – is less glory-bound, and more invested in pity, fear and loss. Tippett's elaboration of the Iliad reminds me strongly of Greek tragedy. Works such as Aeschylus's Oresteia are, in effect, sequels to Homer. The Oresteia answers the question: what happened when Agamemnon, the leader of the Greek troops, got back home? Tippett asks: how did this thing start? How did we get to here?

The opera begins with Priam and Hecuba deciding to have their infant son Paris killed, because Hecuba has dreamed that her child will cause his father's death. The baby is given to a shepherd, who is instructed to carry out the deed – but spares him. The boy is brought up in the mountains, until one day his elder brother Hector encounters him out hunting and, ignorant of his true identity, persuades Priam to bring the boy back to Troy. It is a fundamental trope of folklore, this: the child who is abandoned and then turns up to cause havoc, or become great, or both – similar tales are told of Moses, of Cyrus of Persia, of Oedipus, of Snow White.

Also in the early part of the opera we are brought the judgment of Paris – in which the young man is obliged to bestow a golden apple on the goddess of his choosing, either Hera, Athena or Aphrodite. Each offers bribes, Aphrodite's being the opportunity to possess the most desirable woman in the world. That's Helen, who is already married to Menelaus of Sparta. Paris gives the apple to Aphrodite, and claims Helen, who abandons her husband. And so the Trojan war begins, as the Greeks cross the sea in a mighty fighting force to retrieve the stolen bride.

The keynote of all this – and this is something particular to Tippett's take on Homer – is the role of personal agency. The answer to the question "how did this happen?" is, for Tippett, because people chose. Priam and Hecuba chose to kill their child; the shepherd chose to save him; Priam chose to bring Paris home again. Paris chose Aphrodite. Helen chose Paris. From these operations of the human will disaster spools, inexorably and unstoppably. In the fifth line of the Iliad, we are told that "Zeus's plan was drawing to its conclusion". Zeus and the other gods are active in the poem – weighing in, supporting their favourite heroes, taking up arms. But from Tippett's opera, the gods – aside from Hermes, who acts as messenger and go-between – are banished. Responsibility is made to rest solely with its human characters. At the same time, they are shown to be in an impossible position: there are no right choices.

According to Dennis Marks, who is preparing a biography of Tippett, this profound sense of human responsibility is bedded in the composer's deeply felt pacifism: he chose to spend five months in prison as a conscientious objector in the second world war. Marks, in an essay for Opera magazine, also points out a crucial contrast between Britten's War Requiem and Tippett's King Priam. Through Owen's poems, Britten takes us right into the trenches, gives raw musical life to the experience of combat – still a fresh memory for so many people in 1962. King Priam is, perhaps, the work for today. If the Iliad is a poem of the exterior, its action fought out on the plain of Troy, then King Priam is a poem of the interior, of what happens within the palace walls.

For all the catalogue of brutal slaughter in the Iliad, each kill described in vivid anatomical detail, there is only one death shown on stage in King Priam, just as the work ends, and that is the death of the old king, too feeble to fight. This is an opera about collateral damage. As bombs blow on Syrian highways, and Marie Colvin is slaughtered in her Homs refuge, King Priam speaks to us.

• King Priam is at the Brighton festival on 27 May