Sentry's Order is a military command that instructs soldiers to stop what they are doing and remain in place. The term is often used in the context of a sentry, or guard, who is responsible for monitoring an area and alerting others to any potential threats. The crossword solution for Sentry's Order is 'HALT, ' which is an acronym for 'HALT and listen.' This command is used to ensure that all personnel in the area are aware of the situation and can take appropriate action.