The Duchy of Brunswick (Braunschweig in German) was a part of the old Duchy of Saxony (in now what is called "Lower" Saxony, as opposed to the "Upper Saxony" of the Electorate and Kingdom of Saxony and the Saxon Duchies of Thuringia), named after the city of Braunschweig. Like all mediaeval German states, all the sons of the family shared and shared alike in the common inheritance of the family, and so were all equally Dukes of Brunswick. If collateral lines of descent died out (i.e. had no male heirs, as the Salic Law was observed in Germany), the unity of the realm could be restored. If not, then not. The Duchy of Brunswick was one of oldest states in Germany, with an almost continuous existence under the same ruling family dating back to the 1200s. In the post 1871 German Empire, Brunswick was a cluster of small enclaves located in the Harz Mountains in north- central Germany between Hannover and Magdeburg. In the 1905 census, the duchy showed a population of 485,655, of which 136,162 were in the city of Brunswick alone. Together, the enclaves making up the duchy amounted to 3,672 square kilometers. In time, as attempts were made to institute primogeniture, smaller principalities or duchies (secundogenitures) might be created for younger sons and cousins. The main line of Brunswick was associated with the capital of Lüneburg, while subsidiary domains were created for younger sons, especially in Dannenberg, Wolfenbüttel, Hannover, and Celle. My information on the details of this is spotty. The only domain that eventually became permanently separated from the larger was the Duchy of Brunswick-Wolfenbüttel. In time, that became simply the Duchy of Brunswick, as the larger Duchy, in turn, acquired a new name. That began with the creation of a Principality of Hannover -- usually written Hanover in English -- in 1638. When all but one of the sons of William the Pious (or the Younger) died without male issue, and all of the sons of George Odysseus followed suit, Ernest Augustus reassembled most of the Duchy and then elevated Hanover to Duchy status. When his brother George William, who was rulling Brunswick-Celle and whose daughter Ernest Augustus had married, died in 1705, the whole Duchy was reassembled, except for Brunswick-Wolfenbüttel. The larger Duchy, however, now began to be called Hanover, especially when Ernest Augustus was made an Elector of the Holy Roman Empire in 1692, as "Elector of Hanover." The marriage of Ernest Augustus to a granddaughter of James I of England then gave his son George a claim to the Throne of England and Scotland, realized with the "Hanoveran Succession" in 1714. The fiefdoms that comprised Brunswick came under the control of the Welf (Guelph) family during the reign of Henry the Lion, Duke of Bavaria and Saxony. The first Duke of Brunswick was his grandson, Otto the Child, who was given the title of Duke of Brunswick and Lüneburg in 1235. In the 1600s, the House of Brunswick divided into an elder and a younger line. The elder line would continue to rule Brunswick (then styled Braunschweig-Wolffenbüttel) while the younger line became Kings of Hannover and Great Britain. During the reign of Napoleon, Brunswick lost its independence. Duke Karl Wilhelm Ferdinand had died of wounds received in the battle of Jena in 1806, and the duchy was incorporated into the Kingdom of Westphalia from 1807 to 1813. After a short period of Allied administration, the "Black Duke" Friedrich Wilhelm was returned to his throne. He would die shortly thereafter in the Battle of Quatre-Bras (1815). The line of the Welfs, defeated in Germany, thus many years later came to the powerful Throne of Great Britain and Ireland. The British Parliament was always suspicious of the German interests of the Hanoveran Kings, but Hanover naturally found itself in anti-French alliances just like Britain. After the paroxysm of the French Revolution and Napoleonic Wars, when Hanover was usually under French occupation, the Electorate emerged as one of the Kingdoms of Confederation Germany. A fateful parting of the ways came in 1837, when Queen Victoria came to the Throne in Britain. The Salic Law prohibited female succession, and Hanover passed to her uncle, Ernest Augustus. In 1866, his son, George V, picked the wrong side in the war between Prussia and Austria. The Prussians occupied Hanover and deposed George, who was thrown upon the hospitality of his English cousin. On the death of Duke Wilhelm in 1884, the elder line was extinguished and the throne should have passed to his cousin, the 3rd Duke of Cumberland. Prussia opposed this and the Federal Council of the German Empire placed the duchy under a regency. This regency lasted until 1913 when Ernst August, son of the Duke of Cumberland who had been prevented from taking the throne, married Viktoria Luise, daughter of Kaiser Wilhelm II. Six months after the marriage, Ernst August became Duke of Brunswick and would remain on the throne until 1918. The 3rd Duke of Cumberland had his royal titles, peerages and British citizenship stripped from him by the Titles Deprivation Act on November 8, 1917 and his peerage was stricken in 1919. Thus his son was not only the last Duke of Brunswick but never became the 4th Duke of Cumberland either. Ernst August Prinz von Hannover, son of the last Duke of Brunswick, tried unsuccessfully to have his English titles restored but did succeed in obtaining the right to British citizenship in 1956. One obstacle he faced was that he had been an officer in the German Army in World War Two, serving with the 158th Reconnaissance Battalion (Aufklärungsabteilung 158) and on the staff of Colonel General Erich Hoepner. He had been wounded at Kharkov in early 1943.