They also offered a tactical advantage: they allowed soldiers to rest the butts of weapons firmly against their shoulders, which wasn't feasible with smooth-surfaced plate armours.
[4] Jacks were often made from recycled pieces of older plate armor, including damaged brigandines and cuirasses cut into small squares.
[5] The image opposite shows the internal construction of a reproduction jack being made by a member of The Tudor Group.
After the death of James V of Scotland in December 1542, Cardinal Beaton ordered the keeper of the royal wardrobe John Tennent to give the king's jack of plate to his lawyer Adam Otterburn.
Although they were obsolete in Britain by the time of the English Civil War, many were taken to the New World by settlers like the Pilgrims because they provided excellent protection from the arrows used by Native Americans.