History of the Church vol. 3 is now available as a free e-book on Project Gutenberg! Obviously, HotC is a big deal, and we’ll just let it stand at that. (Unless you have some strange desire to read only about the 1838-39 window of Church history, you really ought to start with vol. 1, and if you’ve already read vol. 1 and 2 you probably don’t need an introduction to 3, so no further commentary at this time.)
It was proofed and produced by our excellent BYU research assistant Mariah Averett, thanks to donor support for her position.
Are there any plans to release the remaining volumes?
Yes, volumes 4-6 are at one point or another in the process and will be coming out eventually.