The issuing of commissions of array was a medieval method of raising troops, originally introduced during the reign of Edward I, by which the King could grant the lords-lieutenant of counties powers to raise military forces in times of emergency. The statute was allowed to lapse at the end of the reign of Elizabeth I but had never been repealed. King Charles I revived commissions of array during the summer of 1642 after Parliament passed the militia ordinance. Although the commissions were criticised even by some Royalists as a dubious and antiquated device, the King urgently needed a means of calling the nation to arms without going through Parliament.
The commissions themselves were written in Latin in an antiquated script upon a roll of parchment. They were signed by the King and impressed with the Great Seal. From June 1642, commissions were issued to every county and large city in England and Wales. Each commission named the leading men of the county or city whom the King believed would support his cause. The commissioners were empowered to call out the trained bands and to persuade them to declare for the King. They were also expected to collect money for the Royalist cause and to send armed men to join the army that the King was mustering. Those appointed commissioners of array formed a nucleus of Royalist county administrators and military organisers throughout the kingdom.
The question of whether to obey Parliament's militia ordinance or the King's commission of array became an early test of allegiance for nobles and gentry.
Sources:
Ronald Hutton, The Royalist War Effort 1642-46, (London 1999)
C.V. Wedgwood, The King's War (London 1958)
