Collection primarily documents Roland J. Regan's experiences during World War II largely through photographs and military memorabilia.

The photographs from 1943 show Regan in combat engineer training in Wales and England, including portraits at the Lakenheath/Mildenhall Royal Air Force base. The photographs from 1944 document Regan and his fellow combat engineers at the 348th Engineer Combat Battalion headquarters in southern England, unloading supplies... on Utah Beach during the week after D-Day, and in Paris in the fall of 1944. The photographs from 1945 show the close of the war in Germany, including Regan and fellow combat engineers building pontoon bridges across the Rhine, Elbe, and Sauer rivers, posing with German artillery, and meeting the Russian army, as well as the aftermath of the liberation of concentration camps. Many of Regan's photographs were published in the book From Boston to Berlin (2001) written by his son Roland J. Regan, Jr. and Christopher Mauriello.

The artifacts include both U.S. and German military memorabilia. The U.S. military memorabilia consists of Regan's dog tags, military emblems, pins, plaques, and ribbon bars. The German artifacts include belt buckles, a knife, a medal, and pins.

The printed materials and ephemera consist of German and Irish postcards, German money, a handwritten song and prayer of the 348th Engineer Combat Battalion, newspaper clippings, and travel brochures. Also included is a history of the 150th Engineer Combat Battalion produced by battalion staff immediately after the war.