The 42nd Division was made up of National Guard regiments from all over the country, hence the "Rainbow" nickname. During training before going overseas, the 69th New York of the old Irish Brigade got talking with some of the boys from an Alabama National Guard regiment around an ice cream truck. Turns out that the Alabama regiment descended from one that was on Marye's Heights at Fredericksburg where the 69th got cut up pretty bad barely 50 years earlier. Apparently what started out as good natured ribbing rapidly got out of hand and a large scale brawl broke out around the ice cream truck. With no clear winner, the fight was broken up and everyone had a good laugh, but it is an interesting example of rivalry and reconciliation. The scene is depicted in "The Fighting 69th" with James Cagney. I first read about it in a March issue of Military Images in the early 80s.