'Caldy' was a British series of three operations ('Caldy I', 'Caldy II' and 'Caldy III') by the Special Operations Executive to protect various power stations and repeater stations in the Milorg military resistance organisation’s D.18 district in southern Norway at the time of the German surrender (March/May 1945).

The 'Caldy I' party comprised only 2^nd Lieutenant Songe-Møller, who was instructed to work for the local district leader of the Milorg (Norwegian military resistance organisation) and to have Milorg groups working for it. The operation was designed to safeguard the Høgefoss and Even Stadfoss power stations, but little detail of this operation has survived.

A. Fjeld and J. Stumpf were parachuted into the same area as reinforcements in 'Caldy II' and 'Caldy III' on the nights of 25/26 April and 2/3 May respectively to protect the Skerka and Nomeland power stations at the time of the German surrender.