Some time during the 1010s, Brian Boru divorced Queen Gormflaith, and she began to engineer opposition to the High King. Around 1012, relations between Brian and Leinster had become so strained that revolt broke out among the Leinstermen. Sigtrygg aligned himself with the forces of Máel Mórda, leader of the revolt, and the chiefs Ua Ruairc, Ua Néill, and others. Together, they defeated Brian's ally Máel Sechnaill near the town of Swords, and Brian for the moment was unable to render assistance.