Alma 43-62 are known as the "War Chapters" in the Book of Mormon.
For teachers, the chapters are divided the following way:
1) Captain Moroni vs Zerahemnah: Alma 43-44
2) Captain Moroni vs Amalickiah: Alma 46-51
3) Captain Moroni vs Ammoron: Alma 52-58
4) Captain Moroni vs the king-men in Zarahemla: Alma 51, 59-62
Since my class was behind, this grouping helped me to pace our lessons and make a plan to get back on schedule.
Each chapter in the book expounds on a chapter from Alma 43-62 and gives clarity as to principles and doctrines to focus on.
I purchased my copy from Amazon.com.
It is also available from DeseretBook.com