When Orson Pratt worked on the 1879 edition of the Book of Mormon, one of the things he did was to make it easier to compare the Isaiah chapters in the Book of Mormon with those in the Bible. Thus, he created the chapters and verses as they were in the King James Version, allowing for the modifications where the Book of Mormon text differed from the original.
The creation of the new chapters makes sense to Bible readers, but it obscures the very different way that the original chapters were created. Our Chapter 12 of 2 Nephi was not originally separated from the text we have in our Chapter 11. That was a change Pratt made to replicate the Bible’s chapters.
Similarly, the original Chapter VIII included all of our chapters 11 through 15. That was the introductory statement and chapters 2 through 5 of Isaiah. The original Chapter IX covered Isaiah chapters 6 through 12. There was a different principle at work in the original chapters, and even though the text of these chapters closely follows the King James Version text of the Isaiah chapters, they did not similarly reflect the way they were broken into chapters.
Dr. John Gee examined the breaks in the original chapters and noted that they conform to a different, and older, logic. They begin with the general equivalent of “he said." Dr. Gee also noted that the chapters were triggered by this statement at the beginning of a new section rather than anything at the end. That is, regardless of the reason the previous chapter might have appeared to end, this statement of authorship triggered the beginning of the new chapter.
Although the Isaiah chapters are obviously very close to the King James Version text, it is interesting that the chapters themselves had a different logic behind them, and a logic that corresponds to an older concept of creating chapters.
The insertion of chapters from Isaiah begins with Isaiah 2 rather than Isaiah 1, which does not appear in the Book of Mormon. Many scholars suggest that Isaiah 1 is a later introduction, and that Chapter 2 begins a separate unit. Thus, the Book of Mormon begins with that separate and complete unit.