In March 1944, Lieutenant Colonel Joerg rejoined the unit, and on 23 April 1944, the Battalion departed Norfolk, Virginia for Italy. Transiting through Oran, North Africa, the Battalion arrived in Naples on 23 May 1944. They trained at Camp Wright in Trapani and Marsala, Sicily during June 1944, before moving to Lido di Roma, near Rome in July. The 551st was attached to six different American units during World War II.
