Illertissen is a town in the district of Neu-Ulm in Bavaria. It is situated approximately 20 km south from Ulm nearby the river Iller.
The coat of arms lent by Erhard Vöhlin in the year 1530 shows an upright standing lion in red, covered by a black bar with three "P"s in silver capital letters. They stand for Pugnamus pro pace (from the Latin), meaning For peace we fight (not "Pugnamus pro Papa" which means "For the Pope we fight" as has been erroneously suggested.)
The oldest evidence of settlement in Illertissen goes back to the beginning of the 6th century A.D. The first documented mention, going by the name "Tussa", was in the year 954. This was on the occasion of the reconciliation by Ulrich, Bishop of Augsburg and the then bishop of Chur, King Otto I., and his son Duke Liudolf of Swabia. The occasion was a military alliance at Lechfeld, with the goal of preventing further penetrations by the Magyars. The three "P"s in the coat of arms may have originated from this event.