In 2259 Captain Pike took the Enterprise to Kiley 279 to rescue Una Chin-Riley and found a pre-warp civilization on the brink of war with a warp-based weapon.
Pike had been on leave and was haunted by his vision of the future, but Admiral Robert April called him back when Una went missing on a first contact mission. On Kiley 279 the crew learned that the inhabitants had seen a starship battle overhead and used what they observed to build a warp-based weapon.
Pike, Spock and La'an Noonien-Singh went to the surface in disguise. Rather than let the planet destroy itself, Pike broke the usual rules and showed its leaders records of how Earth had nearly destroyed itself, persuading them to step back from war.