WASHINGTON — Under a canopy of poplar and oak trees, a team of geophysicists surveyed the forest floor for century-old wartime relics. They positioned an electromagnetic scanner atop the carpet of leaves while the delicate instrument harvested data about objects in the soil beneath.

In 1918, mortars and artillery shells arched toward this spot near the Dalecarlia Reservoir, one of the main water sources for the nation’s capital. But no armies fought here and no soldiers charged up the embankment. Rather, the shells were launched from the wartime research campus to the east at American University, where scientists developed chemical weapons, explosives, bombs and gas masks to use on the battlefields in World War I.

In this centennial of the war’s end, the team working in the woods was a reminder that the Great War had another name — “the Chemists’ War,” a sobriquet reflecting the crucial role of science in the conflict. Alex Zahl, a project manager for the United States Army Corps of Engineers and a self-described World War I buff, mused over the state-of-the-art science detecting remains of experiments dating to 1918.