Norden bombsight
In the 1920s and 1930s, Dahlgren was involved in testing bombsights, including the Norden bombsight, for the Navy's fledgling air forces. But, until World War II, much of the principal work at Dahlgren surrounded the proofing and testing of every major gun in the Navy's arsenal. Most of the work was done at the Main Range Gun Line, which faces down the Potomac River.