Will Kürlich Kerl
Banned
Challenge: Have the Eastern most border of the Dutch Republic/Kingdom of the Netherlands be the Elbe River.
given that Elbe runs east-west all the way to Wittenberge, more than 2/3's of the way to Berlin from the Mouth (it empties at Hamburg) ... sure you're not thinking of Weser? (runs past Bremen and empties at Bremerhaven)
Netherlands-Hannover personal union in the 1800s somehow? A tall order: Hannover needs to survive for as long as it takes for the House of Orange to go extinct and then marry the female heir.
Also in the 19th century a personal union between the Netherlands and another country was not allowed in the Dutch constitution.I don't think that would work this late. The personal union would be between two fully formed states with their own ethnic identities - the Netherlands, proudly independent, neutral, and Hanover, a German principality integrated into the Bund and Zollverein, with a consciously German populace. The two would remain separate, sharing a head of state under different contitutional arrangements. To make territories that are German today part of the Netherlands, it needs to happen before they think of themselves entirely as German. In the Frisian/Platt corner that is possible until fairly late, but after 1800 is too late IMO.