He insists that without understanding the true topography and layout of the battlefield, historians can never fully gainaninsightinto events from the past.
"In the old days, this was the sort of stuff the IRA would kill for, today an enemy could scan some photos and gainaninsightinto a base, " said Mr Black.
The collection also includes some of the earliest colour images from an archaeological site, which have allowed experts to gain further insightinto the painstaking nature of the excavation, the National Trust added.