Here's mine for the Ingman Imperium/Union
(huge swathe of text and backup flags to follow at some point
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EDIT1: The Compleat Flaggery
EDIT2: The Compleat Text
A Brief History of the Ingman Union
Tradition holds that the northeast coast of what is now called the Inguinnian Peninsula [1] to be the ancestral home of the Ingman, or West Germanic, tribes; though recent archaeological finds across the Scandinavian Sea indicate that Firsenland rather than Ingerstrand may have been settled earlier.
By the 700s the peninsula was home to 3 kingdoms – Westingland, Ingerstrand, Mercerrice – sometimes united under a single overlord or King of the Ingwines.
Edred II of Mercerrice was the first Ingwin King to be salvationised by the Francoman missionary Saint Carlobert who later became Christ of Rheims.
Osbert the Hardy spread Salvationism to the Mering Kingdoms when he established his “Overrike [overkingdom] of the Ingwines [2], the Merings [3], and the Albanings [4]”.
The Norse Conquest shattered his imperium though it was to some extent reunited under his great-grandson (albeit via his daughter Edith with Eric II of Tronde) Eric Magnusson, Overking of the North: King of Tronde, King of the Dallanders, King of the Cimmer Dene, King of the Sweer Dene, King of the Ingwines, King of the Mering Isles.
With the collapse of the Northern Imperium into civil war between the Dane and the Norse claimants to the elected throne, most of the Ingman states became independent Kingdoms or Commonwealths but remained disunited.
It took the rise of Renascent Salvationism (protesting the Authority of the ArchChristal Throne) and emergent Nationalism to enable the unification of the Ingman states. Crown Prince Robert of Westingland took advantage of the War of Alban Succession to claim the crowns of Berwicc and Linden [5]. His charisma won over the other Ingwine realms and brought the genius of General Isengard to his side. Together they established the Ingman Imperium over Westingland, Ingerstrand, the Mercer Freerike, Berwicc, Linden, and West Firsenland.
Following the Great War the Imperium expanded to include The Mering Isles, East Firsenland (reunited with the West), and the former Alban colonies of New Dublin and the Iscariote Islands. It also federalised into the Ingman Union: each Royal House could now field candidates for the Imperial Throne; the Imperial Electorate was widened to include the Provincial Parliaments; the Parliaments of each Union Province gained greater autonomy; and the Imperial Council [6] retained only authority over common trade , defence, and foreign policy.
[1] The Peninsula was named Belgica by the Romans and came under the administration of the Sulla Imperator of Albion. Belgica lives in the name of the Bellowmarsh region
[2] The continental Ingmen – Westingland, Ingerstrand, and Mercerrice
[3] The Ingmen across the Sea – Firsenland, the Orkneys, and the Isle Kingdoms
[4] The Ingmen of Albion – Berwicc and Linden
[5] The claim was through the female line and allowable by Ingman law but the Alban Sullarchs followed male line only primogeniture which they used to claim the kingdoms
[6] The Imperial Council consists of the Overking (or more usually his/her appointed Speaker), the Provincial Lord Stewards and their Vice Stewards (or representatives theoreof), and other delegates invited by Imperial Decree