With the dissolution of the Holy Roman Empire in 1806, Bremen-Verden's status as fiefs of imperial immediacy became void; as they had been in personal union with the neighbouring Kingdom of Hanover, they were incorporated into that state.

This area included most of the modern counties (German singular: Kreis) of Cuxhaven (southerly), Osterholz, Rotenburg upon Wümme, Stade and Verden, now in Lower Saxony; and the city of Bremerhaven, now an exclave of the State of Bremen.

At the beginning of the Thirty Years' War the predominantly Lutheran Prince-Archbishopric of Bremen maintained neutrality, as did most of the Protestant territories in the Lower Saxon Circle, a fiscal and military subsection of the Holy Roman Empire.

In 1626, Christian IV, who was also Duke of Holstein, and thus a vassal of the Emperor, joined the anti-imperial coalition of the Republic of the Seven United Netherlands and the Kingdom of England under James I.

In July 1630, Tilly and most of the Catholic occupants were withdrawn, since on 26 June Gustavus Adolphus of Sweden had landed with 15,000 soldiers at Peenemünde, opening a new front in the Thirty Years' War.

For the war being John Frederick accepted Swedish overlordship, while Gustavus Adolphus promised to restitute the Prince-Archbishopric of Bremen to its exiled elected Administrator.

In October, an army newly recruited by John Frederick started to reconquer the Prince-Archbishopric of Bremen and — supported by Swedish troops — to capture the neighboured Prince-Bishopric of Verden, de facto dismissing Verden's intermittent Catholic Prince-Bishop Francis of Wartenberg who ruled 1630–1631, and causing the flight of the Catholic clergy wherever they arrived.

In 1646 Emperor Ferdinand III granted the Free Imperial City of Bremen the requested confirmation (Diploma of Linz [de]).

Bremen and Verden declined from independent territories of imperial immediacy to a collectively governed dominion of a European great power with all the pertaining restrictions and opportunities.

In 1650 Charles Gustav, Hereditary Duke of the Palatinate of Zweibrücken-Kleeburg, since 1649 declared and 1650 recognised heir to the Swedish throne and thereby simultaneously to Bremen-Verden's dukedoms, came to Stade for interlocutions of unknown content.

In 1381 the city of Bremen had captured de facto rule in an area around Bederkesa and westwards thereof up to the lower Weser stream near Lehe (aka Bremerlehe).

Ferdinand III ordered Queen Christina of Sweden, who was his vassal as Duchess, to compensate the city for the damages caused and to restitute Lehe.

In July 1654, the emperor ordered his vassal, as duke, Charles X Gustav of Sweden, who had succeeded Christina after her abdication, to cease the conflict, which resulted in the First Stade Recess [de] in November 1654.

Sweden and Swedish Bremen-Verden protested sharply, when in December 1660 the city council of Bremen rendered homage to Leopold I, Holy Roman Emperor.

In 1663, the city gained seat and vote in the Imperial Diet, strongly opposed by the representatives of the Swedish Duchies of Bremen and Verden therein.

Asked in 1700 what to do by Charles XII of Sweden, Bremen-Verden's General Government recommended to concede Bremen's status as a Free Imperial City.

Therefore, Christian Albert, Duke of Schleswig and Holstein at Gottorp inherited the county, but ceded it to his father-in-law Frederick III, King of Denmark and Norway,[4] Administrator of the Prince-Archbishopric of Bremen and the Prince-Bishopric of Verden from 1635 until he had been expelled by the Swedish occupants in 1645.

Both powers entered into a dangerous competition for the exclusive opportunity to levy the lucrative tolls from ships heading for Hamburg and Bremen, with the former at that time being a ducal Bremian and the latter a comital Oldenburgian privilege.

As in Sweden proper, the constitutional and administrative bodies in the Swedish dominions gradually lost de facto importance due to ever growing centralisation.

So the Prince-Electorate of Brunswick and Lunenburg, or colloquially called after its capital, the Electorate of Hanover; (German: Kurfürstentum Braunschweig und Lüneburg, or Kurhannover) took de facto possession of Bremen-Verden and stipulated in the Treaty of Stockholm of 1719, settling the war with Sweden, to compensate the latter by 1 million rixdollars.

Being a Prince-Elector of the Holy Roman Empire and represented in its Diet by virtue of his Electorate of Hanover, George II Augustus didn't bother about Bremen-Verden's status of imperial estate.

In the summer of 1757, the French invaders defeated Prince William, Duke of Cumberland, son of George II and leading the Anglo-Hanoverian army.

But also in Bremen-Verden men were drafted in order to recruit the 16,000 Hanoverian soldiers fighting in the Low Countries under British command against Revolutionary France.

In 1795, the Holy Roman Empire declared its neutrality, which of course included the British Electorate of Hanover, and a peace treaty with France was under negotiation until it failed in 1799.

After Britain — without any ally — had declared war on France on 18 May 1803, French troops invaded the Electorate of Hanover on 26 May and installed — among others — two occupation companies in Bremen-Verden's capital Stade on 18 June.

According to the Convention of Artlenburg from 5 July 1803, confirming the military defeat of Hanover, the Hanoverian army was disarmed and its horses and ammunitions were handed over to the French.

In December, the First French Empire, since 1804 France's new form of government, ceded Hanover, which it didn't hold anymore, to Brandenburg-Prussia, which captured it early in 1806.

[10] In 1807 France replaced the Privy Council and the Hanoverian estates of the realm, as announced on 20 September, by its own occupational government, the Commission du Gouvernement (German: Commission des Gouvernements) under Governor General Jean Jacques Bernardin Colaud de La Salcette [fr], and further installed a subdelegate, Peter Christian Dodt, replacing Bremen-Verden's deputation (decision-taking body), however, allowing Bremen-Verden's government (executive body) to work on.

Even though Bremen-Verden's status as a territory of imperial immediacy had become void with the end of the Holy Roman Empire in 1806, the Duchies were not right away incorporated in a real union into the Hanoverian state.

From 1739 on the presidents were in personal union reeves (German: Greve or Gräfe) of the Land of Hadeln: Source[18] Luneberg Mushard [de], Bremisch- und Verdischer Ritter-Sahl Oder Denckmahl Der Uhralten Berühmten Hoch-adelichen Geschlechter Insonderheit der Hochlöblichen Ritterschafft In Denen Hertzogthümern Bremen und Verden.