Seaward

G 617 g was the Forerunner designation for a planet in the G617 system situated within the near border region of the galactic Halo.

Background
It was capable of supporting life, but possessed no indigenous fauna. A Primary Pioneer Group was dispatched to investigate, making a post landfull report. For one reason or another however, it failed to make a follow up report. It appears that a medium intensity military expedition was sent in after 333 hours (or about 14 daysz).

G 617 g1
A moon in the G617 system, G617 g1 was the first world in the Milky Way to be infected by Flood.

A Forerunner-based research team called the Primary Pioneer Group made active landfall on the bordering town planet known as G617g and they initially reported some interesting findings. Despite previous assumptions and conjectures, the world could support sentient life despite the lack of fauna, which they intended to review more closely. The protocol allows them to dispatch a secondary batch of researchers called the Advance Survey Team-Alpha. After a week of no communication, the Forerunners who were remotely monitoring this new discovery become worried.[1]

In their response to the initial testimony and report, those monitoring it advised that they would send a military detachment to the site shortly to uncover why their two exploratory teams have halted communication. That would be the last time the Forerunners had any contact with G617g, and it was the beginning of the largest war their galaxy would ever see, lasting about three centuries. No one knows why the Flood were dormant on G617g or even how long they had been there before they were discovered, but it is believed that they, due to their vastly different physiology, traveled to our galaxy from another.[2]

Trivia

 * There are references to 7 in "G 617 g". "g" is the seventh letter of the alphabet and as such, 6+1+7=14=7+7
 * This is the site where the Forerunners made first contact with the Flood.