In order to get this achievement you need to get an S ranking in mission 15,
Into the Light while playing in campaign mode.
I recommend playing on hard as you will get substantially more points. The mission has two parts with 3 sub-objectives each:
Part 1You need to breach through the enemy lines. Focus on taking down the enemy warships. Note that even if you have destroyed all warships, the mission will only continue after some time has elapsed. Destroying all enemies might speed up the process.
Sub-objectivesDestroy the warship escort of the S Battleship
Destroy the S Battleship
Destroy all enemies
Part 2You need to destroy the two S-Battleships.
Sub-objectivesBoth Destroyers escorting the Acropolis survive
Allied Battleship VINSON survive
Both battleships escorting the VINSON survive
Keep in mind that if you die on the second part and opt to
retry rather then restart the mission you will loose all points from the first part and likely not get an S ranking.
I recommend using the Maelstrom Bomb to destroy enemy ships. You can fly back to your carrier and reload if you run out of ammo. Don't be afraid to cause some friendly fire. The allied warplanes that are affected by your bombs don't reduce you score enough to cause serious damage to your rank. Avoid downing allied ships though!
Resources: Sub-objective list taken from
GameFAQs by
Major Rebirth (formerly known as The Reb1rth).