It is believed that on the site of present day Memmingen in the time of the Romans there was a small military town, probably called Cassiliacum. In the 5th century an Alemanic settlement was established and in the 7th century a palace of the king of the Franks' .
Memmingen was connected to Bohemia, Austria and Munich by the salt road to Lindau. Another important route through Memmingen was the Italian road from Northern Germany to Switzerland and Italy. Both roads helped Memmingen gain importance as a trading centre. In the Middle Ages, the place was known as Mammingin; in 1158 the Welfian Duke Welf VI founded the town of Memmingen. In 1286 it became an Imperial City, responsible only to the Kaiser.
Christoph Schappeler, the preacher at St. Martin's in Memmingen during the early 1500s, was an important figure during the Protestant Reformation and the Peasants' War. His support for peasant rights helped to draw peasants to Memmingen. The city first followed the Tetrapolitan Confession, and then the Augsburg Confession.
The Twelve Articles: The Just and Fundamental Articles of All the Peasantry and Tenants of Spiritual and Temporal Powers by Whom They Think Themselves Oppressed was written (probably by Schappeler and Sebastian Lotzer) in early 1525. This was a religious petition borrowing from Luther's ideas to appeal for peasant rights. Within two months of its publication in Memmingen, 25,000 copies of the tract were in circulation around Europe. These are the first humanrights in the world.
In the 1630's Memmingen was at centre stage during the Thirty Years' War, and the Imperial generalissimo Wallenstein was quartered in the town when he was dramatically dismissed from service. From 1632 Memmingen was briefly garrisoned by the Swedish army, and became a base of operations for Swedish troops in Swabia.
Following the reorganization of Germany in 1802, Memmingen became part of Bavaria. The 19th century saw the slow economic deterioration of the town, which was halted only with the building of a railroad following the course of the River Iller.
Since World War II Memmingen has been a developing town, with a rate of economic growth above the average for Bavaria.
Memmingen has considerable tourist interest, mainly because large areas of the medieval old town survived both World War II and the tasteless post-war reconstruction which has ruined many other German cities. The old town contains many interesting houses of patricians, some in the baroque style. Also of interest is the Stadtbach (town river), surviving sections of town wall as well as a medieval market place and a town hall built in renaissance style. Also famous is St. Martin's church, built in gothic style.
Every year Memmingen celebrates the Fischertag (Fisherman's day), recreating medieval traditions. Every four years Memmingen re-enacts the events around the visit of Wallenstein in 1630.