Here is the full list of all 40 Defend The Highlands achievements.
Recruit 1,000 Scotsmen in total
Get 500 kills with Queen Boadicea
Kill 1,000 enemies with porridge cannons
Kill 500 enemies with whisky vomit
Kill 1,000 enemies with haggis catapults
Kill 1,000 enemies with golf balls
Get 500 kills with William Wallace
Kill 10,000 enemies
Kill 250 enemies with bagpipe artillery
Kill 500 enemies with cheese wheels
Kill 500 Beefeaters
Kill 500 Leprechauns
Kill 500 Welsh Sheep Riders
Complete a skirmish match on hard
Complete a skirmish match on medium
Kill 500 enemies in melee
Kill 1,000 enemies with turnip turrets
Kill 500 Ancient Briton Warriors
Kill 15 enemies with Nessy in a single match
Complete a skirmish match without towers
Kill 500 Posh Englishmen
Get 500 kills with Robin Hood
Fully upgrade all stats on a single unit
Hit 5 enemies with a single artillery strike or haggis
Get 500 kills with Alfredo
Have 5,000 porridge at once
Complete a skirmish match on easy
Complete a skirmish match without heroes
Defeat a level 6 enemy on level 1 in skirmish mode
Kill 1,000 enemies with porridge bowls
Have 50 Scotsmen at once
Kill 500 English Cricket Players
Kill 500 Irish Potato Farmers
Kill 500 Welsh Rugby Players
Have 2,000 gold at once
Kill 1,000 enemies
Fully upgrade a stat
Complete a skirmish match on impossible
Recruit 100 Scotsmen in total
Kill 100 enemies