Donnchad's first venture was a campaign against armies of the Foreigners in modern County Louth, "in which a very large number [of the Foreigners] were slaughtered."[REF]
On Donnchad's death, he was succeeded as King of Tara by his sister's son, Congalach Cnogba, a member of the Síl nÁedo Sláine branch of the Uí Néill.