Complex sentence: During his last years, he privately published two volumes of poetry, left one volume unpublished, and returned to prose of the sea: the novella "Billy Budd", left unfinished at his death, was published in 1924.
Split into simpler sentences: During his last years, he privately published two volumes of poetry, left one volume unpublished, and returned to prose of the sea. The novella "Billy Budd" was left unfinished at his death but was published in 1924.