Through his mother he was first cousins with Empress Maria Theresa On the suggestion of his court-preacher, Johann Friedrich Wilhelm Jerusalem, in 1745 he founded the Collegium Carolinum, an institute of higher education which is today known as the Technical University of Brunswick.

Lorenz Heister of the University of Helmstedt named the botanical genus Brunsvigia in his honour, in recognition of his encouragement of botany and the study of B.

[1] Charles attempted to promote the economic development of his state; for example, he founded the Fürstenberg Porcelain Company, and he installed mandatory fire insurance.

When the American Revolution began in 1775, Prince Charles saw an opportunity to replenish the duchy's treasury by renting its army to Great Britain.

In 1776, Duke Charles signed a treaty with his cousin George III of the United Kingdom to supply troops for service with the British armies in America.