[2] King Charles I wanted Lichfield re-taken and turned into a Royal garrison, because the Royalists were in considerable need of ammunition, and their chief supply was drawn from the northern counties.

The convoys had, however, to pass through districts sympathetic to Parliament and as: "the enemy was much superior in all the counties between Yorkshire and Oxford, and had planted garrisons so near all the roads that the most private messengers travelled with great hazard, three being intercepted for one that escaped,"[3] A Royalist party little inferior in strength to an army was necessary to convoy any supply of ammunition from Yorkshire to Oxford.

[4] Among the orders given to Rupert for the Lichfield expedition was that he should teach the population of Birmingham a lesson for their disloyalty to the Crown, both for being a manufacturing arsenal for Parliament, and especially for the insults they had put on the King in October, 1642, before the Battle of Edgehill, in plundering the Royal Coach.

[4] After the Royalist victory at the Battle of Camp Hill, Rupert stayed in Birmingham overnight and on Easter Tuesday, 4 April, he marched to Walsall; and the next day he reached Cannock, where he halted.

[6] The siege was continued until Friday, 21 April, when Rupert again ordered an assaulted the place and this time the Royalists took it with a help of an explosive mine — said to have been one of the earliest used in England — blowing up part of the wall of the Close.