Here is the full list of all 12 Victory At Sea Ironclad achievements.
Destroy 750 enemy ships.
Destroy 40 enemy blockade runners.
Destroy 40 enemy frigates.
Destroy 40 enemy gunboats.
Destroy 40 enemy ironclads.
Destroy 40 enemy rams.
Destroy 40 enemy sloops.
Destroy 40 enemy steamers.
Capture 20 enemy ports.
Complete the Union campaign.
Complete the Confederate campaign.
Destroy 3 enemy ships in a battle involving only one ship of your own.