Here is the full list of all 20 Medieval Kingdom Wars achievements.
Win a Field battle in Campaign Mode
Win a Siege Attack battle in Campaign Mode
Complete the Tutorial
Win a Town Defense battle in Campaign Mode
Start up the game
Conquer London in Campaign Mode
Conquer Paris in Campaign Mode
Conquer Frankfurt in Campaign Mode
Conquer Madrid in Campaign Mode
Conquer Zaragoza in Campaign Mode
Conquer Lisbon in Campaign Mode
Conquer Granada in Campaign Mode
Conquer Dijon in Campaign Mode
Conquer Glasgow in Campaign Mode
Conquer Dublin in Campaign Mode
Conquer Vienna in Campaign Mode
Conquer Prague in Campaign Mode
Conquer Avignon in Campaign Mode
Conquer Venice in Campaign Mode
Win a Naval battle in Campaign Mode