[1] The 121st Engineer Battalion traces its lineage to the 5th Infantry Regiment of the District of Columbia National Guard.

The 37th had been alerted for movement to England, and sent its 112th Engineer Combat Battalion ahead as part of the advance party.

On 6 June 1944, the 121st Engineer Combat Battalion landed on Omaha beach in Normandy with the first American forces.

The unit endured much damage to its equipment and casualties among its soldiers, but after some recovery it continued to assist in the invasion.

[3] The new battalion played a pivotal role in the crowd control efforts after being called in to assist the local authorities during the race riots that took place in Baltimore and Cambridge in the 1960s.