A unit citation is a formal, honorary mention of a military unit's specific and outstanding performance, usually in battle, which is granted by a higher authority.
During her thirteen year service the crew of the USS Dauntless earned three unit citations. The first citation was granted after the Dauntless held off a group of Romulan warbirds from taking a disputed area of the Alpha Quadrant until other vessels could arrive to lend assistance.
The second citation was gained in 2374 when, during the Battle of Tyris, the Dauntless assisted the USS Lionheart in protected two damaged Akira-class vessels from an attack by a large force of Cardassian warships.
The third citation was gained during the Final Battle in 2375, when the badly-damaged Dauntless was able to provide cover for the flagship and fought off four suicide attacks by Dominion vessels. (TNG video game: Bridge Commander)