town, capital of Gers departement, Midi-Pyrenees region, southwestern France. Auch is built on and around a hill on the west bank of the Gers River, west of Toulouse. The capital of the Celtiberian tribe of Ausci, it became important in Roman Gaul as Elimberris and, after Christianity was established, became the metropolis of Novempopulani. In 732, to protect against Muslim raiders, the town was moved across the river to its present site. It was the seat of the dukes of Armagnac in the Middle Ages, and it became the capital of Gascony in the 18th century.
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