[i]"The Prophet of Truth's ships breached the Lunar Perimeter. Smashed what was left of the Home Fleet." -Cutscene, Crow's Nest, Halo 3[/i] When Truth arrived with reinforcements, the month long war above Earth suddenly ended when our defensive perimeter around Earth was destroyed. Any surviving ships either fled Sol, took refuge at secure locations on Earth, or probably retreated to the edges of the Sol System. Another possibility would have been hiding in the asteroid field. The first option being taken isn't likely at all given what was at stake. Although, given the fact that Truth's ships were mainly focused on Kenya, it's also possible that some UNSC ships could have remained in orbit around Earth keeping a wide berth from Truth's ships.