A Shadow of Doubt
In July 1945, when the British forces withdrew from all German territories they had conquered that were provided to be occupied by another Ally, the British military government ceded some smaller sections of their zone to the Soviet Zone, specifically the Hanoverian Amt Neuhaus and some Brunswickian exclaves and fringes (e.g. County of Blankenburg). Within its zone the British military government restituted the traditional German state of Hamburg (but in borders drawn by the Nazis in 1937) and established the new states of Schleswig-Holstein (formed in 1946 from the Prussian Province of the same name), Lower Saxony (a merger of the restituted Free States of Brunswick, Oldenburg and Schaumburg-Lippe with the Prussian province of Hanover in 1946) and North Rhine-Westphalia (a merger of the restituted Free State of Lippe and the northern part of the Prussian provinces of the Rhineland (with the southern part under French occupation) and Westphalia in 1946–47). In 1947 by a redeployment the restituted traditional German state of Bremen became an exclave of the US Zone of Occupation within the British zone. The military government, officially Control Commission for Germany – British Element, headquartered in Bad Oeynhausen.
Much of the British Zone was once part of the Kingdom of Hanover. Hanover was in a personal union with Britain from 1714 to 1837.