This word, used in the singular number, designates a nation at war with the United States, and includes every member of such nation. Vatt. 1. 3, c. 5, 70. To make a public enemy, the government of the foreign country must be at war with the United States; for a mob, how numerous soever it may be, or robbers, whoever they may be, are never considered as a public enemy. 2. A common carrier is exempt from responsibility, whenever a loss has been occasioned to the goods in his charge by the act of a public enemy, but the burden of proof lies on him to show that the loss was so occasioned.