Notice the name of the enemy ace pilot in the pic above. Yes, Grieg is back and waiting at Fort Monus for payback. Resupply and go get him. Reaching the area, you find Grieg piloting a "Sea King" Type without proper training just to get you. Yeehin states the "Sea King" Type is the newest model from Sakata Industries, being large but fast at the same time.

7 Missilers in ARPEGGIO Lv 16 HP 456 (Body 144 Arms 204 Legs 108) FI 85 ST 0 LG 24 AG 188

3 Attackers in PRISOMEA Lv 17 HP 408 (Body 132 Arms 168 Legs 108) FI 0 ST 105 LG 0 AG 162

3 Missilers in TYPE65 Lv 16 HP 402 (Body 132 Arms 156 Legs 114) FI 77 ST 0 LG 37 AG 156

2 Carriers in Natural Lv 16 HP 200 (Body 200) FI 0 ST 24 LG 0 AG 205

Grieg in SEAKING Lv 12 HP 580 (Body 580) FI 0 ST 76 LG 0 AG 411

Military Commission 20000

Destroyed Enemy Bonus 13609

As you can notice, the enemy unit is crowded with missilers (which can be annoying before you reach them) , but your only real threat is Grieg in the Sakata wanzer. Luckly, he's still at the same level from the last time you fought him, but don't underestimate him. Destroy all other units before attacking Grieg.

Finally Fort Monus has been taken. But the war isn't completely over yet, so go for your next mission