This cursory description of an historical ballad has a direct bearing on the term as used in the instrumental form. The historical ballad tells a story in verse with or without music, while the Romantic era ballad is an instrumental work. More specifically, in the case of Chopin's use of the term, it is a musical composition for solo piano that tells a story in purely musical terms.
When the first ballade was published in 1836 it was considered somewhat of a novelty at the time, for no composer had used the term for a work for solo piano before Chopin. Chopin wrote four ballades (the spelling he used derives from French) during his lifetime, from 1831 to 1842. During his second trip to Vienna in 1831, he began to write the first ballade. He completed it in 1835 after he had moved to Paris. Each of the 4 Ballades are singular works. There are a few purely technical similarities between them, but musically and emotionally they are separate pieces. They contain some of the most difficult technical and interpretive challenges of any pieces for solo piano in the repertoire.
Lento - The ballade begins with seven bars of slow arpeggios in common time that serves as a recitative/introduction to the work.
Moderato - The short introduction blends into the first of two primary themes, a gently pensive theme in 6/4 time and the home key of G minor. After this theme is repeated and slightly expanded, a motive is heard and passage work leads to the second major theme with the indication,
Meno mosso - This theme is in E-flat major. This theme gets a proper hearing and elaboration, and leads up to the next section.
What has gone on before may be considered as the exposition of a piece in Chopin's personal use of sonata form, as the first theme reappears. It gradually leads to the reappearance of the second theme in a more powerful rendering in a different key. Another motive is heard, and leads to what can be considered as a recapitulation, although the themes appear in reverse order than they did in the exposition. A stunning coda begins, complete with powerful runs in both hands alternating with solemnly quiet chords until a thunder of octaves brings the piece to a close.
In the end, no amount of analysis, slight or detailed, will convey the strength of Chopin's artistry in this ballade. Or is there anything of much value to trying to tie the ballade with any kind of literary work. Chopin made no reference to any outside inspiration. It is as Chopin intended; a story told in purely musical terms to be understood by emotions and feelings brought on by the music. In that aspect, Chopin is one of the most Romantic of all Romantic era composers.