The Mis-throw at Belach Eóin

Fíacha Fíaldána Dimraith came to have speech with the son of his mother's sister, whose name was Maine Andóe. Dócha mac Mágach came with Maine Andóe and Dubthach Dóel Ulad came with Fíacha Fíaldána Dimraith. Dócha cast a spear at Fíacha and it went into Dubthach. Then Dubthach cast a spear at Maine and it went into Dócha. The mothers of Dubthach and Dócha were also two sisters. Hence the name Imroll Belaig Eúin, the Miscast at Belach Eúin.

—Or, according to another version, the origin of the name Imroll Belaig Eúin is as follows:

The hosts came to Belach Eóin. Both armies halted there. Diarmait mac Conchobair came from the north from Ulster. ‘Send a messenger,’ said Diarmait, ‘asking Maine to come with one man to parley with me, and I shall go with one man to meet him.’ Then they met. ‘I have come from Conchobar,’ said Diarmait, ‘to ask you to tell Medb and Ailill that they must let all the cattle (they have taken) go and their depredations will be overlooked. And let the bull from the west be brought hither to the bull (Donn Cúailnge) that they may encounter each other, for so Medb has promised.’ ‘I shall go and tell them,’ said Maine. So he gave the message to Medb and Ailill. ‘These terms cannot be got from Medb,’ said Maine. ‘Well then, let us exchange weapons,’ said Diarmait, ‘if you prefer.’ ‘I am willing,’ said Maine. Each of them cast a spear at the other and both of them died, so that Imroll Belaig Eóin is the name of that place. The army rushed upon the opposing force. Three score of them fell on each side. Hence the name Ard in Dírma.