Aerial photography was a key tool for the military to develop a plan of attack and to keep an eye on the enemy.
Before World War 2, Theodore Rowhel pretended to be checking out new commercial air routes for the German airline, Lufthansa. Disguised in a civilian plane, with hidden cameras, he flew over and photographed the coastline of Scotland and England.
During the war, this became a standard duty of the Luftwaffe, the German military air force. To avoid detection by British fighter planes they usually flew at a height of 30,000 feet.
Today the Royal Commission on the Ancient and Historical Monuments of Scotland holds copies of the wartime spy photographs of Scotland taken by the Luftwaffe.
Germany used these images for intelligence work. This included selecting targets to bomb, assessing bombing accuracy and identifying the location of anti-aircraft defences. Today they are a fascinating resource for investigating German military strategy.
A German spy plane photographed the military camp and port at Loch Alsh on 29 September 1940. The area was a potential target for German planes to bomb. Highlighted on the photograph was the location of Balmacara's sister anti-aircraft station (B1). Alongside Balmacara (B2) to the east, it was a threat to the success of any planned attack.