BGSU’s Center for Archival Collections has a variety of local manuscripts available online. While reading through the “Annie R. Stuart Diary” I found this entry:
Sunday, June 9, 1861
All went to the french church to see them march and try to kill the devil. There was a great many there. Did not all march. Some of us sat at the foot of the cross until we were tired and we went to the edge of the woods and stayed with the others a short time. George asked me to take a short ride which we did and had a pleasant time. They returned from their march and bowed at the alter. We left. Went to church. 3 of the students here. Very tired.
Since the diary mentions locations throughout the rural Tiffin area, I’m thinking the church is Frenchtown St. Nicholas. The date would be the Feast of Corpus Christi, so perhaps the Luxembourger immigrants had some type of festivity as described at the link below.
Further speculation welcome . . .