In the early morning of 22 October 1946, Soviet officers, each with an interpreter and an armed soldier, went to the homes of selected German specialists in the Soviet zone of occupation and took them to the Soviet Union. German Wikipedia gives more than 2,500 specialists. Most worked in aviation and rocketry, nuclear research, chemistry and optics. Almost 300 of them were specialists in optics and glass. The operation served to secure the transfer of know-how. Many family members were taken with them. Sources give different totals.