Quick reply --
Most Civil War artillery shells were fused. They were supposed to air burst and have shrapnel cause the majority of casualties. Some exceptions here, including most naval artillery, but by-and-large if you see air bursts in and around a target area during a land battle then it is relatively/generally accurate.
Tank HE rounds, on the other hand, are mostly impact rounds. Today, in fact, HEAT rounds are the HE round. In the past, there were experiments and regular tank shells that did have fuses (the "beehive" round comes to mind); however, most tank rounds are direct impact fused.