Military Observation Balloons of WWI: Before Satellites And Drones, these Hot Air Balloons Were Used For Surveillance
#10 An observation balloon is launched near Ypres, Belgium to spot enemy artillery, 1917.
WWI

Military Observation Balloons of WWI: Before Satellites And Drones, these Hot Air Balloons Were Used For Surveillance
#10 An observation balloon is launched near Ypres, Belgium to spot enemy artillery, 1917.
WWI