The Marsi (German: Marser) were a small Germanic tribe settled between the Rhine, Ruhr and Lippe rivers in northwest Germany. It has been suggested that they were a part of the Sugambri who managed to stay east of the Rhine after most Sugambri had been moved from this area.Strabo describes the Marsi as an example of a Germanic tribe who were originally from the Rhine area, now the war-torn Roman frontier, but had migrated deep into Germania.
Tacitus mentions them repeatedly, in particular in the context of the wars of Germanicus. They had been part of the tribal coalition of the Cheruscian war leader and traitor to Rome, Arminius that in 9 AD annihilated three Roman legions under Varus in the Battle of Teutoburg Forest. Germanicus, seeking revenge for this defeat, invaded the lands of the Marsi in 14 AD with 12,000 legionnaires, 26 cohorts of auxiliaries and eight cavalry squadrons. The Marsi were massacred during a festival near a temple dedicated to Tamfana. According to Tacitus, an area of 50 Roman miles was laid to waste with fire and sword: "No sex, no age found pity."