Though the Prophets may be dead, the war is far from over. After the brief peace treaty forged by the UNSC and Sangheili, Thel 'Vadam didn't return to Sangheilios just to celebrate the 'costly victory', he returned to regroup with the Covenant and strike the ponies while they deal with the lost of the Master Chief. As the UNSC tried to rebuild Earth's colonies, the Covenant attacked once more now under the command of Thel 'Vadam. Over the years the UNSC returned the Spartan program to give them some kind of edge against the reformed Covenant threat. After the loss of Noble Team and Master Chief's Blue Team missing, the UNSC hasn't had a strong and reliable Spartan team until Harmony Team was formed. By direct orders for the High Princesses themselves, Harmony is Pony-kind's new hope against the looming shadow of the Covenant.