Bagrationovsk (bəgrŭˌtyēôˈnəfsk) [key], town, NW European Russia, formerly in East Prussia, on the Polish border. Its German name was Eylau or Preussisch Eylau. It is a rail terminus and has meat-processing and dairy industries. The town was founded in 1336. In Feb., 1807, it was the site of a bloody, indecisive battle between Napoleon I and the allied Russian and Prussian forces that checked Napoleon's movement toward the Russian frontier. The town is named in honor of Gen. P. I. Bagration, who distinguished himself during the battle.