Operation: FIRST STRIKE
From Halopedia, the Halo wiki
this operatin is among the UNSC most incredible raids conducted by only a handful of marines and spartans the mission recalled that the spartans plant a *Nova nuclear bomb on the center of a Covenant combat station. And even with the odds been on the Covenant side the infiltration forces do sucess.Only months later the Covenant sweep aside all of the UNSC defenses and attack the most prized of all planets...Earth.
