the map of Germany was not unlike the picture of a stupid helmeted giant, sprawling on all-fours, with a pygmy master on top.
This was just a textual description, but check out Dogs of War at BibliOdyssey for a series of actual satirical maps in this vein; the descriptions are so similar that I suspect that the writer of the Cassell's piece must have had such a map in mind. First the Cartoon, then the War: Europe in 1870 at Strange Maps gives the same treatment to the Franco-Prussian War.
Strange Maps has many more maps with various intents: politics, humour, fantasy, and so on. Skimming, highlights include the classic Charles Joseph Minard map ("The best statistical graphic ever drawn" - see also Revisions of Minard - a multimedia graphic of the harrowing outcome of Napoleon's 1861 march on Moscow); World Government Plan: Aliens to Police USA (a concept, not unlike that in Piers Anthony's SF novel Triple Detente, in which peace was maintained by swapping governments; London's Lost Rivers (one of my topics of interest - see Underground London); Holmes, Sweet Holmes: A Floorplan of 221B Baker Street; and Where On Earth Was Middle-earth? - UCLA geophysicist Peter Bird's mapping of Middle Earth on to European geography, apparently in the recent geological past with lower sea levels.
Oddments connected by theme: Map of Inland (post-apocalyptic Kent in Russell Hoban's Riddley Walker, from Riddley Walker Annotations); A Buyers Guide to Maps of Antarctica by Catherynne M. Valente, Clarkesworld, May 2005 (this is a story about the rivalry between two cartographers, one devoted to realism and accuracy, the other to creating fantastical maps).
Other previous map-related posts here: Hardy perennials; and Mountweazels and other fictions.