Ernest Augustus was born on 17 November 1887 in Vienna, Austria-Hungary [now Austria]. He was married to Viktoria Luise von Preußen. He died on 30 January 1953 in Hanover, Lower Saxony, Germany.
He lived to see one of his children become a consort to a monarch - in 1947 his daughter Frederica became Queen of the Hellenes when her husband Prince Paul of Greece and Denmark succeeded his brother as King. The Duke of Brunswick is also the maternal grandfather of Queen Sophia of Spain and the former King Constantine II of Greece.