Final answer:
General Thomas Jackson's nickname is 'Stonewall,' earned during the First Battle of Bull Run. The information on Andrew Jackson as 'Old Hickory' is not relevant to this question.
Step-by-step explanation:
General Thomas Jackson was famously known by his nickname “Stonewall” Jackson, a moniker he earned during the First Battle of Bull Run in the American Civil War due to his steadfast and immovable defense, much like a “stone wall.” Unfortunately, the reference information provided speaks of Andrew Jackson, not Thomas Jackson. While Andrew Jackson, also a notable general and the seventh President of the United States, was known as “Old Hickory,” this nickname is not applicable to General Thomas Jackson.