Army Meritorious Unit Citation Criteria: The Army Meritorious Unit Award (MUC, MUA) is awarded to units of the United States Army who show exceptional meritorious conduct in their performance of duties for a period of at least 6 months during conflict with an armed enemy. While service in a combat zone in not necessary, their service must be directly related to the combat effort. Subsequent awards of the citation are displayed by wearing a Oak Leaf Cluster on the service ribbon.