The invasion of Normandy had 34 NCDUs. When the first ten arrived in England they had no CO. Lt. Smith(CEC) assumed the role, splitting them up to train with the 146th, 277th and 299th Combat Engineers. As more NCDUs arrived they did the same, with 5 combat engineers attached to each NCDU. Group III(Lt. Smith) did research and development and is credited with developing the Hagensen Pack. NCDUs had a 53% casualty rate at Normandy. Four from Utah beach later took part in Operation Dragoon.