Sentinel

A soldier posted to. guard an army, camp or fort from danger or surprise; a sentry. Sentry Board. — Small floor boards about 3ft inches square and with additional cro pieces underneath, giving them a height of about a foot, thus raising them well out of the mud. They are used in the trenches and are very handy before a platform is made, and in some cases are used for small men after the fire platform is made.