In 58, Julius Caesar had invaded Gaul. After some initial successes against Helvetian migrants, he realized that they were not the only people who wanted to settle in Gaul, and by the end of the year, he was facing a coalition of Germanic tribes led by Ariovistus. It has been suggested that this battle took place north of modern Colmar.
Friends of mine who were on a hiking trip in the Elsace visited the place and took some photos. They are now available here. I hope they did not forget to see the Isenheim Altarpiece, which is of course a better reason to visit Colmar.