It depicted what would supposedly become of Europe following a German victory, showing Germany having taken great swaths of land from the surrounding countries, and having transformed Britain into a colony.
I'm fairly certain it was British, at least.
Is this the map you're thinking of?
It seems to have circulated around the internet plenty, but I can't find any provenance beyond people describing it as WW1-era Franco-British propaganda; a horror story of what would happen if the Germans won the war.
The map shows a 'Greater Germany', stretching from the Atlantic coast of France to Petrograd (St Petersburg) in Russia, with Britain and Ireland as colonies; and a vastly-expanded Austro-Hungarian Empire controlling Moscow/Muscovy and the Ukraine down to the Black Sea.
The linked image is in French, but the caption below notes that it was first published by the Daily Mail, a British newspaper. My (very) rough translation of the text below:
The Dream of German Hegemony: what defeat would cost us
We publish above, from the Daily Mail, a map showing German's proposed redrawing of Europe after the war, which shows what we would have become if the German plan had succeeded.
Belgium, Luxembourg, Serbia and Montenegro disappear completely. Russia loses all of its territories, including Petrograd. Great Britain becomes a German-Austrian colony. As for France, it is reduced to the département of Basses-Pyrénées, with Bayonne as its capital.
