An English* scholar of the late 19th century, David Munro, compared [the Iliad and the Odyssey] and discovered an interesting phenomenon (now known as Munro’s law), which is that there is no overlap in their contents: neither poem recounts any events that are told in the other. This discovery lends itself to several conclusions… but the most likely is that they were designed to complement one another. The Odyssey seems, in fact, to go out of its way to fill in the rest of the story of the Iliad. Not only does it give a comprehensive account of the “Returns” [nostoi] of the Greeks, but it finishes the story of the war itself, recounting events that are implicit but still untold at the end of the Iliad: the death and burial of Achilles and the taking of Troy.
Sheila Murnaghan in the introduction to Stanley Lombardo’s translation of the Odyssey
*Munro was born in Scotland, but spent his career at Oxford.