Jeff, I can contribute a bit regarding your inquiry. If he was captured on 5 July after the battle, chances are good that he had been wounded, either on 1 July or 3 July. The exceptions would be that he was sick (odds are perhaps 1-3%) or else that he had served in a support role such as the ambulance "corps," or was a musician, and thus would been ordered to stay behind to care for the wounded (a few percent of men in a regiment would fit this category). Incidentally, the latter category of hospital attendants would all have typically been captured on 5 July; such was the case with the 55th's surgeon and assistant surgeon for instance. I have analyzed the casualties in the 55th: listed casualties on 1 July are 14 officers and 261 enlisted men, and on 3 July 11 officers and 63 men. Those having an unknown date are 3 officers and 38 men, and if these are apportioned to 1 or 3 July based on the above percentages (the regiment was not engaged on 2 July), we arrive at an estimated 17 officers and 291 men who were casualties on 1 July, and 12 officers and 71 men who were casualties on 3 July. So based on the numbers, the regiment took significantly higher losses on the first day. In addition, the figures on 1 July include at least 5 officers and 120 men who were captured unwounded, and nearly all these were taken prisoner by the 6th Wisconsin at the railroad cut in the morning action. I don't know of any sources with information on Thomas Neal, but if I was forced to guess in the absence of an extant account, I'd have to say the two most likely choices in this case are either that 1) he was an attendant taken prisoner while serving in a field hospital on 5 July, or 2) that he was actually captured on 1 July while in line of battle with his regiment.