system
Given the following post, respond as if you're commenting on Reddit:
human
[Halo] What is so important about Reach and why was it's fall a major event in history?

Was it a strategically important location or was it purely just the Covenant saying "look we can knock you on your ass even at your strongest fortresses" hoping to demoralize humanity?
gpt
Reach is at Earth's metaphorical doorstep, being 10.5 lightyears away from the Sol system. It was the nexus of the UNSC military command, Humanity's 2nd most populous colony, and a major producer for the UNSC's war material and recruits. It's titanium mines are the largest sources for humanity.

Its fall to the Covenant meant that the UNSC just lost its second most largest source of its logistics to rearm, resupply, and replace any lost military units. It meant that the Covenant were now closer to Earth and therefore closer to eradicating humanity. It meant that the UNSC could no longer mount offensive operations to reclaim any of the Outer Colonies either lost to the Covenant or went dark to avoid genocide.

Most importantly, the Fall of Reach was the impetus to Spartan John-117 and the *Pillar of Autumn* to discover the Forerunner Installation 04 and hence, the eventual victory of humanity over the Covenant.