The Bonfire Societies have long-standing traditions about who marches where in the processions. There are typically groups of members who all dress in the same costume. Those in the first group are called the (1st) Pioneers; those in the second group the 2nd Pioneers. The image shows Commercial's 2nd Pioneers in 1998, dressed as soldiers from the American Civil War.
Soldiers detailed to carry out duties similar to those of mdern combat engineers such as cutting roads, repairing bridges and works, and dismantling enemy artillery, fortifications, and railroads; the Pioneer Corps was a specialized unit in the Army of the Cumberland.