Career
John Ernest (German: Johann Ernst) (10 May 1521 – 8 February 1553) was a Duke of Saxe-Coburg. After the death of his father (1532), his half-brother, John Frederick I, assumed the title of Elector of Saxony. John Ernest took part with him in the rule over the Electorate of Saxony.
In 1542 John Frederick I decided to rule alone, and ceded to John Ernest the Franconian areas of the Wettin family lands (Coburg, Eisfeld, etc).
But it was not until 1547 (after the Battle of Mühlberg) when John Ernest could govern undisturbed in Coburg.