Following information on the 115th First Maryland Infantry Regiment courtesy Wikipedia:
On 3 February 1941, the First Maryland Infantry Regiment, Maryland Army National Guard, was inducted into Federal Service as the 115th Infantry Regiment at Frederick, Maryland as part of the second partial mobilization of the National Guard for World War II, and then moved to Fort George G. Meade on 18 February 1941 to join the 29th Infantry Division.
The regiment completed in-processing, traded in its equipment for modern equipment, and started to repeat its Division Level training. It was then transferred to the A.P. Hill Military Reservation on 22 April 1942 to participate in Maneuvers, and then moved to the Carolina Maneuver Area to participate in large unit maneuvers on 8 July 1942. It then moved on to Camp Blanding to fill its empty personnel slots on 19 August 1942, and then Staged at Camp Kilmer on 20 September 1942, and shipped out from the New York Port of Embarkation on 5 October 1942 on the RMS Queen Mary and RMS Queen Elizabeth.
They arrived in England on 11 October 1942, and then were attached to the U.S. 1st Infantry Division in preparation for the D-Day invasion. They moved with the 1st ID from 2 June 1944, and remained with 1st ID until 7 June 1944, when they returned to the 29th ID for further operations. Their participation in the Normandy Campaign continued until it was over on 24 July 1944. They immediately moved into the Northern France Campaign on 25 July 1944, which continued until it was over on 14 September 1944.
During this period the 115th Infantry Regiment was engaged in a one of the wars forgotten chapters, "The Battle of Brest". The Battle for Brest was one of the fiercest battles fought during Operation Cobra, the Allied breakout of Normandy which began on 27 July 1944, during the Battle of Normandy during World War II.