lose hill and win hill

So why is it called Lose Hill?

From here:

On the northern side of [Hope village], Win Hill and Lose Hill are very prominent features and there is a ancient legend about how they acquired their names from a battle in 626. Rivals King Edwin of Northumbria was camped on Win Hill and King Cuicholm of Wessex on Lose Hill. The army from Wessex was much the larger, so Edwin ordered his men to build a stone wall around the summit of the hill. When the battle commenced both sets of troops advanced, but the superior numbers soon started to push Edwin’s forces back. Once the order to retreat came, the Wessex troops sensing victory, charged forward, only to be crushed to death by a hail of boulders heaved down the hill by Edwin’s men to win the battle.