In 1870, Prussia fought a six-month war with France that would result in a humiliating defeat for the latter and the creation of Germany in its modern form. Serving in the Prussian army at the time were some 4,700 Jews, some of whom were present at the siege of the French fortress city of Metz, which began on August 19. Daniel Lipson writes:
The German Jews who were among the soldiers maintaining the siege must have hoped that it would end before the Jewish High Holy Days. But Rosh Hashanah came, and the siege of Metz remained in place. The Jewish soldiers were allowed to hold prayers, but there were no chaplains to handle the preparations and lead the ceremonies. A young rabbi named Isaac Blumenstein took up the task, arriving at the military camp on September 30, just before Yom Kippur. The prayers were to take place at the First Army headquarters in the village of Sainte-Barbe, about eight kilometers from the battlefield.
The rabbi was offered to hold the Yom Kippur prayers in a local Catholic church. He refused and instead turned his and his neighbor’s personal quarters into a makeshift prayer space. Two candles were placed on a table that substituted as the bimah, and some 60 to 70 soldiers gathered there for the prayer.
The German artist Hermann Junker (who was not Jewish) created two paintings commemorating the Yom Kippur prayer during the siege of the city of Metz in 1870. . . . This painting is based on a description written by an anonymous soldier before Yom Kippur that was published in the Jewish press after the holiday. His description noted that 1,174 Jewish soldiers from Silesia and Poznań were planning to attend the prayer. The soldier wrote that, with God’s grace and in the hopes that the French commander—that is, the enemy—would allow it, the prayer would take place in an open field.
Read more on The Librarians: https://blog.nli.org.il/en/lbh_kol_nidre_german_1870/?_