It takes its name from a 16th-century tract by John Knox opposing female rule, titled The First Blast of the Trumpet Against the Monstruous Regiment of Women.

The cover illustration of the British edition, by Paul Kidby, is a parody of Joe Rosenthal's photograph Raising the Flag on Iwo Jima.

[1] The small, belligerent country of Borogravia is a highly conservative nation, whose people live according to the increasingly strange decrees of its deity, Nuggan.

These things include garlic, cats, the smell of beets, people with ginger hair, shirts with six buttons, anyone shorter than three feet (namely dwarves, children and babies), sneezing, jigsaw puzzles, chocolate (which was once Borogravia's staple export, plunging the country into increasing poverty), crop rotation (which degraded Borogravia's soil and reduced already scarce food supplies), and the colour blue.

Thanks to a chance encounter where the regiment unknowingly subdue and humiliate an elite Zlobenian detachment, including Prince Heinrich, their exploits become known to the outside world through William de Worde and his newspaper, The Ankh-Morpork Times.

In the midst of this revelation, the Duchess, now raised to the level of a small deity by Borogravians' belief, takes brief possession of Wazzer, her most passionate believer.

Borogravians Zlobenians and other neighboring countries Ankh-Morporkians The New York Times felt that Monstrous Regiment "had serious heft", comparing Pratchett's depiction of "the pity of war" to Wilfred Owen.

[2] The Chicago Reader, addressing the 2014 stage adaptation, considered it to be largely "a satire on the flimsiness of traditional gender roles",[3] while Publishers Weekly noted its "astute comments on power, religious intolerance and sexual stereotyping".

[5] PopMatters felt that the book lacked subtlety, but was "more than one-dimensional", commending Pratchett for "manag[ing] to walk right on the edge of proselytizing without ever quite crossing over" and for showing that there is no "clear-cut solution" to the issues which led to the Borogravian conflict.

[6] BuzzFeed, however, was far more negative, calling it "clunky", and ranking it last among the adult-oriented Discworld novels published prior to the announcement of Pratchett's diagnosis with Alzheimer's disease.