 Complete the following phrase:  As part of the 2nd Airborne Brigade alongside a sister unit, the 508th Parachute Infantry Regiment, the 507th PIR was assigned to the veteran 82nd All American Airborne Division, commanded Major General Matthew Ridgway, to replace the 504th Parachute Infantry Regiment, which had suffered many casualties while serving, with distinction, in the fighting in Italy. The regiment arrived in the United Kingdom in late 1943, and began training and preparing for the invasion of Normandy, scheduled for the spring of 1944. Their D-Day objective during Mission Boston, part of the 