Combat Center Marines and first responders conducted a hazardous material scenario at the post office, May 21, 2014, when postal clerks discovered a suspicious package. The scenario was a part of Postal Exercise 2014, a training exercises that tested Marines and responders aboard the Combat Center. - Combat Center Marines and first responders conducted a hazardous material scenario at the post office, May 21, 2014, when postal clerks discovered a suspicious package. The scenario was a part of Postal Exercise 2014, a training exercises that tested Marines and responders aboard the Combat Center.