The First Battle over Avalon took place in orbit near the Unified Earth Government colony of Avalon and was one of the few naval victories of the Human-Covenant war, greatly thanks to the efforts of United Nations Space Command Fleet Admiral, Dalton van Schie, and his successor Ava Grieve as well as the crew of UNSC Arthur's Excalibur and many other sailors of the UNSC Navy. The battle was fought to a standstill with the UNSC forces losing a total of half their defensive fleet, an Orbital Defense Platform and several cruisers and the Covenant attackers suffering the loss of a majority of their fleet remainder being repelled or disabled by the unusually well equipped Avalon Defense Fleet led by the UNSC Ouranos.