Which command is used to bring a squad to a halt during a drill?

The command used to bring a squad to a halt during a drill is "Halt." This command is specifically designed to signal the members of the squad to stop their movement immediately and stand still. It serves as a clear and concise directive that ensures everyone in the squad understands they must cease all activity and remain in place.

This command is fundamental in drill instructions because it aligns with the principles of discipline and order that are essential in military and other formal drill contexts. It creates a moment of pause where attention can later be redirected or commands for further actions can be issued.

The other choices do not serve the same purpose as "Halt." For instance, "At ease" allows individuals to relax in stance but does not instruct them to stop movement. "Stand at attention" demands a specific posture while still preparing for movement or further commands, and "Fall out" indicates that personnel can leave their formation or may be dismissed from duty. Therefore, "Halt" is the most appropriate command for bringing a squad to a precise stop during a drill.