This is the fourth book in the series which began with "Ghost" and continued with "Kildar." I have seen the series described by the names of both those books and also "Paladin of SHadows."
Can I begin this review with an apology to Amazon customers for the convoluted title above, which results from an attempt on my part to correct how the book was originally wrongly described.
When "Unto the Breach" was first listed on Amazon, the words "Legacy of Aldenata" were wrongly given after the title. John Ringo's "Legacy of Aldenata" series are military SF set in a universe where Earth was invaded in 2005 by ravenous aliens called the Posleen: that series starts with "A Hymn before battle" and includes titles like "When the devil dances", "Cally's War" and "Hero.")
This book is nothing to do with the Posleen universe, so I fired off to Amazon a suggested correction, which has been accepted and implemented. Overestimating the sophistication of the systems involved, I included an explanation for the correction, which appears above as if it were part of the suggested description of this book. DOH !
"Unto the breach", like the second and third books in the series, is less outrageous, and a bit better written, than "Ghost" but still pushes the envelope hard in several places. As a rough litmus test, if you were strongly against the Iraq war, are very pro-feminist, or even slightly prudish, do your blood pressure a favour and refrain from touching this entire series with a ten foot barge-pole.
Former SEAL Mike Harmon, codename Ghost, after fighting and defeating a number of terrorist plots, has settled down in a remote valley in the country of Georgia where he bought the local castle. It turns out that the castle and associated farmland came with some feudal retainers, the Keldara, who accept him as their liege lord or "Kildar" - and if that sounds wierd and anachronistic at the start of the 21st century you ain't read nothing yet.
Since Chechen terrorists are a major nuisance in the area on both sides of the Georgian/Russian frontier, Mike Harmon has trained some of his Keldara as an anti-terrorist militia with the knowledge and support of the Georgian, Russian, and US governments. He has also smashed a criminal conspiracy in which senior figures in the governments of most of the world's most powerful governments were implicated. The guilty individuals concerned have been quietly removed from power, but now Mike Harmon has both friends and enemies in all those governments.
"Unto the breach" begins when unknown assailants raid a secret Russian weapons reseach establishment. It soon becomes apparent that a "doomsday weapon" has fallen into the hands of some of the worst possible people. Mike Harmon and the Keldara are asked to help deal with it - this may be the most important, and difficult, mission he has taken in his life.
The full "Paladin of Shadows" series currently consists of
Ghost
Kildar
Choosers of the Slain
Into the Breach
A Deeper Blue
John Ringo normally writes military SF and most of his offerings in that genre are extremely good. This series is about a freelance war on terror. In places, and especially in the first book, Ringo seems to be in grave danger of crossing the line between challenging the reader and going out of your way to see how many people you can offend. That goes even for his existing fans among military SF readers, who are probably neither the most prudish or left/liberal of audiences.
In fact the funniest part of "Unto the Breach" and all the other books in the series from "Kildar" onwards is not part of the main text - it is the disclaimer at the start of the books which at least demonstrates that Ringo understands and has a sense of humour about the controversy "Ghost" stirred up. That disclaimer is worth quoting in full, it reads as follows:
"This is a work of fiction. All the characters and events portrayed in this book are fictional, and any resemblance to real people or incidents is purely coincidental. This book and series has no connection to reality. Any attempt by the reader to replicate any scene in this series is to be taken at the reader's own risk. For that matter, most of the actions of the main character are illegal under US and international law as well as most of the stricter religions in the world.
"There is no Valley of the Keldara. Heck, there is no Kildar. And the idea of some Scots and Vikings getting together to raid the Byzantine Empire is beyond ludicrous.
"The islands described in a previous book do not exist. Entire regions described in these books do not exist. Any attempt to learn anything from these books is disrecommended by the author, the publisher and the author's mother who wishes to state that he was a very nice boy and she doesn't know what went wrong."
Incidentally, that line about "any resemblance to real people or incidents is purely coincidental" is a classic example of a blatantly false statement which escapes being a lie only because both author and reader know that it's a legal fiction which he has to write and makes no attempt to fool anyone. Osama Bin Laden and Vladimir Putin appear in these books under their real names, certain other characters will instantly be recognised by any politically aware reader as corresponding to real world US politicians.
All five books in the series contain a great deal of violence, strongly expressed and very right-wing political views, and a lot of references to sex, always utterly politically incorrect and sometimes fairly explicit. My copies of these books are stored where my children can't get at them and will be until they are adults.
Provided you are not offended by the sex, violence and non-PC attitudes, these books can be quite exciting and entertaining in places. But I would advise feminists, left-wingers, and anyone even slightly prudish to save your money for something else.