What is Articles Of War?

Legal Definition
The Articles of War are a set of regulations drawn up to govern the conduct of a country's military and naval forces. The phrase was first used in 1637 in Robert Monro's His expedition with the worthy Scots regiment called Mac-keyes regiment etc. (in the form "Articles of warres") and can be used to refer to military law in general. In Swedish, the equivalent term Krigsartiklar, is first mentioned in 1556. However, the term is usually used more specifically and with the modern spelling and capitalisation to refer to the British regulations drawn up in the wake of the Glorious Revolution and the U.S. regulations later based on them.
-- Wikipedia
Legal Definition
The name commonly given to a code made for the government of the army. The act of April 10, 1806, 2 Story's Laws U. S. 992, contains the rulesand articles by which the armies of the United States shall be governed. The act of April 23, 1800, 1 Story's L. U. S. 761, contains the rules and regulations for the government of the navy of the United States.
-- Bouviers Law Dictionary
Legal Definition
Codes framed for the government of a nation's army are commonly thus called.
-- Black's Law Dictionary