A Civil War gun battery was established at Cranstal in 1643 but was ineffective, and by 1656 was 'neglected and ruined.'  Its site remains unlocated. Three pre-18th century demi-culverin guns are known near Cranstal; two used as gateposts at Ballachrink. A fourth cannon was taken from Kerrowdhoo to Derby Fort A tradition says that a stream in the area was bridged with cannon.