The Second Battle of Harvest, also known as just simply the Battle of Harvest, was humanities first attempt to recover the planet Harvest from the Covenant, who wiped out the existing colony and killed tens of thousands of civilians a year earlier.
The UNSC sent Battle Group X-ray, forty warships led by the UNSC Everest and Vice Admiral Preston Cole, to retake the colony from the Covenant. Harvest was defended by a single Covenant super-destroyer, which managed to destroy thirteen UNSC warships before it was ultimately destroyed.
The Second Battle of Harvest was the first chapter in the Harvest Campaign, a five-year campaign to remove all Covenant from the planet and retake the colony world.
These events are depicted in the comic Halo Wars: Genesis which was the subject of a Halo Book Club episode on February 9th, 2017 and short story The Impossible Life and Possible Death of Preston J. Cole in the anthology Halo: Evolutions which was the subject of a Halo Book Club episode on January 3rd, 2018.