[2] His sister Charlotte married the Elector of Hanover, King George III of the United Kingdom on 8 September 1761.

[3] Shortly after being widowed for a second time in December 1785, Charles requested permission to retire from his military employments in Hanover and resign the governorship.

[2] Following the death of his childless older brother Adolf Friedrich IV on 2 June 1794, Charles succeeded him as the ruling Duke of Mecklenburg-Strelitz.

[5] As ruler, Charles encouraged new agricultural trends, established a new police force, and implemented compulsory education.

After Friederike's death in complications of the birth of their tenth child in 1782, Charles married her sister Princess Charlotte of Hesse-Darmstadt on 28 September 1784 in Darmstadt.