in may 1940, the german army invaded the netherlands and belgium. the british military authorities were determined that the large oil installations at the major ports should not fall into enemy hands. the kfre were despatched in secrecy on 11 may to amsterdam to negotiate with the local commanders and destroy the installations and the large oil stocks and assist with dockyard demolitions; these were called "xd operations". they were successful in spite of the lack of planning and specialised equipment. after amsterdam, detachments carried out more oil demolitions at rotterdam and antwerp, and assisted with the evacuation of 40 tons of dutch gold from rotterdam. at times they exchanged fire with german advance patrols.