Hanover – Flag in Lexicon and Shop https://www.flaggenlexikon.de/fdthanno_me.htm
Hanover was the Electorate of Brunswick-Lüneburg between 1692 and 1810, from 1814 to 1866 the Kingdom of Hanover and from 1866 to 1946 it was a Prussian province, which became a free state on 23rd of Aug. in 1946, which was dissolved on 1st of Nov. in 1946 in the state of Lower Saxony. Its flag – which can also be ordered on this page – originally showed a white Saxons Ross on a red background.
Königreich Hannover, Jürgen Kaltschmitt, Uniform-Fibel