What is so exceptional about the poem Errantry?
Errantry is a three-page long poem that was first published some time in 1933; Tolkien commented it as “most attractive.” It consists of trisyllabic assonances with a metre that Tolkien invented, which was so difficult and complicated that he never wrote another poem again in this style, but he later did develop another style from this, and the result was EƤrendil the Mariner.