Ems or Bad Ems (bät ĕms) [key], town (1994 pop. 10,130), Rhineland-Palatinate, W Germany, on the Lahn River. Chartered in 1324 as an important lead and silver mining center, it has been one of Europe's most famous spas since the late 17th cent. It was the site of the Congress of Ems (1786), which acted to reduce papal influence in the German Catholic Church. Bismarck drew up (1870) the Ems dispatch there.