On Weathertop the heir of Bilbo Baggins is pierced by a weapon of the Enemy and begins to become a wraith. Tolkien first told this story (about Bingo Bolger-Baggins) around autumn 1938. Notes for the story to come set down in Bree do not mention Weathertop. The incident appears to have written itself, and compelled its author to look at the world through the eyes of a wraith. This was a startling vision, the first glimpses of which propelled Tolkien on a path to Lothlórien by way of a lecture on fairy-stories.

Just before this incident, as the party make their way to Weathertop, Trotter (a hobbit) tells that in ancient days Elendil and the Elfking made a strong fort on the top of the hill. This passing  historical observation catapulted the story from the days of myth into the days of legend after Númenor. To begin to understand what this means we must already have understood the myth of the ruin of Númenor – which was the point of composing Apprenticeship, the ebook that sets out the second part of this study of the making of The Lord of the Rings.

We now have the elements before us to understand how a story that in 1939 was still envisaged as around the same length as The Hobbit became The Lord of the Rings