In order to unlock the achievement, you need to complete the 4 campaigns of the game which are The Normans, The Rise Of Moscow, The Hundred Years War and The Mongol Empire. I included videos for every mission of every campaign on hard difficulty to give you an idea how to beat them quickly and effectively.
Campaigns (Longplay):The Normans:The Rise Of Moscow:The Hundred Years War:The Mongol Empire:The Normans Campaign:1066: The Battle Of Hastings:1069: North To York:1105: The Fall Of Bayeux:1106: The Battle Of Tinchebray:1119: The Battle Of Brémule:1141: First Battle Of Lincoln:1153: The Siege Of Wallingford:1216: The Siege Of Dover:1215: The Siege Of Rochester:1217: Second Battle Of Lincoln:The Rise Of Moscow Campaign:1238: Rebuilding Moscow:1375: Tribute:1380: The Battle Of Kulikovo:1382: Hold Against The Horde:1478: Fall Of The Novgorod Republic:1480: Great Stand On The Ugra River:1514: Moscow Versus Lithuania:1552: The Siege Of Kazan:The Hundred Years War Campaign:1351: The Combat Of The Thirty:1360: The Siege Of Paris:1364: France In Chaos:1370: The Battle Of Pontvallain:1429: The Siege Of Orléans:1429: The Battle Of Patay:1448: Retake Normandy:1450: The Battle Of Formigny:The Mongol Empire Campaign:1223: The Battle Of The Kalka River:1213: The Great Wall:1215: The Battle Of Zhongdu:1240: The Siege Of Kiev:1241: The Battle Of Liegnitz:1241: The Battle Of Mohi:1267: The Song Fortress:1268: Blockade At Lumen Shan:1273: The Fall Of Xiangyang: