GSBD: The Descending Sword ( 105 Dagger, No Respawn, S Rank)
The ninth Earth Alliance '71' Mission and the first with an S rank objective that really requires you to know it's there with one of the enemy you need to take out only spawning if you enter close to the base doors behind your starting point.
To start with the enemy will be in groups of four with a DINN, two GINN and a Vosgulov ship quickly take out the enemy group before quickly taking out the ship then dash over and take out the other one, at around this time Mu should spawn in to 'help' but may go down before he finishes talking so take out what's shooting/shot him down then enter the base entrance area to spawn a new enemy depending on if you can take him out with one SP attack ( Hyper mode, Super shot and so one) he might turn invincible if he does so put some distance between you and him as the DINN has poor range and help the Archangel until you can damage him again during this or just after Kira should arrive bringing the time limit to leave the area and the enemy Duel so clear out a GINN or two for meter before dealing with it, the Archangel will take a beating depending on how long it takes you to handle the fine so clear it out before retreating to the safe area.
For the second part of the mission be carful if you chouse to chase after the enemy in front of you as the GINN are very capable of firing there missiles and charging in will get you hit by multiple, if your not fast enough or comfortable in going after the group in front you can take the 'grounded' GINN out before turning you attention to the group that will spawn behind you, as long as you got both enemy ace units in the first half of the mission you don't need to be too worried about taking out enemies as long as you are getting some to bolster your points total.
As usual you have better suits available to you so obviously use them for an easier time.
The initial go through where i didn't know about the hidden enemy is here • mission 9 for the sake of transparency.