On the main menu select Skirmish
Change your Home town/Civilization to French (Paris) (The flag Icon next to your gamertag)
Select Deck Builder -> Beginner
On row IV remove the icon for 4 Cuirassiers with the infinite symbol by clicking on it.
Select IV: Industrial Age
Select the 6 Cuirassiers card to place it in your deck.
Click Save and then back
Change starting age to Post-Imperial Age
Start the game and enter the cheat code: Nova & Orion
Select the flag icon in the bottom right corner of the screen (next to the mini map)
Choose the Beginner Deck
On line IV Select the 6 Cuirassiers option
This will deliver 6 Cuirassiers to your Town center and will pop the achievement.
Enter cheat code speed always wins to speed this up a bit.
Note: This has to be done using the 6 Curiassiers card.