"This siege has been conducted through the hottest part of the season,—July, August and September,—yet the troops have suffered but little from excess in heat, on account of the large proportion of night work, and the almost continual sea-breeze, which was always cool and refreshing.
"The amount of sickness was great, the large amount of duty being the probable cause. On the 7th of August the percentage was the smallest observed during the siege, being 18.6. At this date the aggregate garrison of Morris Island was 9,353, of which 1,741 were sick. On the 17th of August 22.9 per cent. of the whole garrison were on the sick list. This was the most unhealthy period of the siege.
"The average strength of the command on Morris Island during the siege was, of all arms, 10,678 men, of which the average percentage sick was 19.88. The number of black troops varied from 1,127 to 1947.
"Average percentage of sick in Artillery, 6.2; ditto, in Engineers, 11.9; ditto, in Black Infantry, 13.9; ditto, in White Infantry, (excluding one brigade), 20.1.
"This brigade consisted of the Ninety-seventh Pennsylvania, Twenty-fourth Massachusetts and Tenth Connecticut Volunteers. It averaged thirty per cent sick. This was due to the fact that these three regiments had been stationed, before moving to Morris Island, on Seabrook Island, which proved very unhealthy. The engineers and black infantry were employed exclusively on fatigue duty. The white infantry served as guard of the trenches, as well as for work in the same.
"Details from the troops on Folly Island took part in the operations on Morris Island.
"It was found by experience that men under these circumstances could not work more than one-fourth the time. A greater amount at once increased the sick list. Eight hours in thirty-two, or eight hours on and twenty-four off, was found to be the best arrangement, as it made a daily change in the hours of duty for those regiments permanently detailed for work.
"The organization found most advantageous in working a command permanently detailed for fatigue duty, was to divide its effective force into four equal detachments, on duty eight hours each, relieving each other at 4 a. m., 12 m. and 8 p. m. The large number of extra troops employed in the trenches each night were usually changed daily.
"The engineer officers in charge of the works were divided into corresponding groups, four in each, relieving each other at 8 a. m., 4 p. m., and 12 midnight, four hours different from the time of relieving the troops. This difference enabled the engineer officers to carry the work through the period of relieving the fatigue details.
"One engineer officer, having from two to four different kinds or jobs of work to superintend, was found to work advantageously in the night, with the help of non-commissioned officers of engineers, from one hundred to two hundred men.