The Concord Dawn conflict happened during the time of the Mandalorian Civil War.
Death Watch, a dissident Mandalorian group led by Vizsla, launched an assault on the planet Concord Dawn. Concord Dawn was home to a significant population of Mandalorians devoted to the "True Mandalorian" faction, which was under the leadership of Mandalore Jaster Mereel, who had been born on Concord Dawn. The True Mandalorians were scattered, and Death Watch spent several days hunting them down.
The man who took over Mereel's position as Journeyman Protector after Mereel's banishment, sheltered Mereel and his forces at his homestead. Consequently, the homestead was obliterated, and the Protector, along with his wife, was killed by Death Watch. Only his two children, Jango and Arla Fett, survived the attack. Jango aided Mereel in defeating Death Watch by guiding him away from the homestead and toward the nearest town. Arla was later saved and placed in a mental institution on Coruscant.
After assuming victory in the conflict, Vizsla intended to attack Moonus Mandel next, but first needed to resupply and recover. As Death Watch entered the town, the Mandalorians launched an ambush, destroying their armored vehicle. Fett himself planted the explosive and eliminated a high-ranking Death Watch member. However, Vizsla ultimately managed to escape.