The weather is very hot. I was on camp guard today when one of the guards suddenly became sick. I was number 24 in the first relief, and the man next to me, number 25, got sick. He called out to me, "Corporal the guard number 25.'' It then became my duty to repeat the same call, "Corporal the guard number 25," to the guard next to me, number 23, who made the same call to the guard next to him, and in this way the call went down the line to guard No. 1. Guard number 1 then sent the same call to the corporal of the guardhouse, who went out to guard number 25 to see what he wanted. When he was found to be sick another guard was brought out to relieve guard number 25.
Source: Alexander G. Downing, Edited by Olynthus B., Clark, Downing’s Civil War Diary, p. 62