Enlisted in the Eastern Association army, Packer was a trusted lieutenant in Oliver Cromwell's cavalry regiment by 1644. A religious radical, Packer clashed with Major-General Lawrence Crawford, who had him arrested for disobedience.
Enlisted in the Eastern Association army, Packer was a respected second-in-command in Oliver Cromwell's cavalry unit by 1644. A devout extremist, Packer disagreed with Major-General Lawrence Crawford, who had him detained for insubordination.