Ethelfrith believed that all the arrangements were originated by himself when the army set out from Bambrough in two divisions, to fight one of the most decisive battles in the dawn of our history.
It was in the autumn of the year 603 that the battle was fought which finally settled the question of supremacy between Scots and English. Sivel had already introduced the system of counting time _Anno Domini_ among the associates of the Coelred-_Gemót_, which was a valuable help to them, both in discussing the past and forecasting the future. This year was a great epoch in their lives. Lilla and Bassus were comparatively veterans. All the rest were about to fight in their first battle.
Ethelfrith's army was in the upper part of the Eden valley. It was known that a mighty host was being led by Ædan and by Hering the son of Hussa up the course of the river. Bassus had arranged with his friends that strong parties of scouts should be thrown out to watch the movements of the enemy. They were led by Forthere, Godric, and Sivel. After a few days Forthere came back with the news that a large body of the enemy, apparently nearly half their army, had been detached, and was marching up the hills to the west. "Our plan works," said Bassus to Lilla, "just as the plan of Narses worked, our great master in the art of war." "But," said Lilla, "the King's brother is not another John the Prefect. The reckless Theobald will never avoid an action." An hour afterwards Ethelfrith sent a message to his brother with reiterated commands to retreat before the advancing foe. Then the English host, by rapid marches, hurried down the valley and attacked the weakened army of Ædan with overwhelming force. The result was never doubtful. The Scots were nearly exterminated, and Ædan fled almost alone from the field. After two days to rest and recruit their strength, the English warriors were fresh and ready to complete their work. Then a messenger arrived with the news that Theobald had refused to obey his brother's orders. He would retreat before no man, he declared. He attacked the superior force of the enemy when weather and ground and everything was against him. He gave himself no chance. There was a desperate fight, followed by the death of Theobald and a prodigious slaughter of the Bernicians. But the Scots were reported to be much weakened and worn out with long marches.