|Season One, Episode 19|
|Air date||April 24, 2014|
|Written by||Mike Herro and David Strauss|
|Directed by||Chris Grismer|
|<font-family:Trajan Pro;font color="white">Episode Guide|
- "Let me have an example of you, to my other problems by grinding you into the dust you no longer see fit to sweep!"
- —Queen Catherine
For Love Or Country
When Mary’s uncle, the Duke of Guise (Gil Darnell), arrives in France with devastating news about her mother, Mary and Francis realize they are torn between putting their own countries first or saving their marriage. With the English throne in jeopardy, King Henry hatches an elaborate plan that will end in disaster. Meanwhile, Sebastian and Kenna solidify their marriage and begin to trust one another - The CW
Queen Catherine: I wouldn't be so smug dear. You just let the devil into our home.
Duke of Guise: Nonsense. Don't trouble yourself over niceties. I don't.
Duke of Guise: From what I hear, even when your father is present, the King is 'no longer in the castle'.
Queen Catherine: Surely a bounty of demeaning tasks awaits you in the kitchen.
Queen Catherine: Nothing brothers me more than problems I’ve already solved coming back to be problems again.
Queen Catherine: Let me have an example of you, to my other problems by grinding you into the dust you no longer see fit to sweep!
Queen Catherine: Don't make friends with rats. They bite.
Mary Stuart: Trust is a luxury I can no longer afford.
- 'Toy Soldiers' are what children use when playing. Referring to someone who is inexperienced in war, or carless with their men.
- James Stuart was mentioned, but does not appear.
- This marks the first appearance of Duke of Guise and Greer's family.
- This episode's Timeline takes place weeks after the last episode.
- This episode spans over almost two months.
- This episode marks the first time Kenna and Sebastian consummate their marriage. 
- Penelope was locked in The Tower for three to four weeks, and Greer's family were staying at the castle for at least a few weeks as Mary was shown writing her letter to her uncle and then when he had arrived time clearly had elapsed. After he arrived Penelope was let out of the tower, and Greer's family left court.
- King Henry mentions he has illegitimate children all over the country.
- Adelaide Kane wore a Temperley London Long Aya Show Dress in White/Gold with a Custom Made by Costume Department dying the winter snow fight. She was later seen in a Vera Wang Embroidered Silk-Chiffon and Mesh Vest, and some beautiful Oscar de la Renta Gold-Plated Lapis Lazuli Earrings.
- King Henry had many illegitimate children, including a son with one of Mary, Queen of Scots' Ladies-in-Waiting, Mary Fleming's mother, Lady Janet Stewart in 1551.
- Credit Order
|Adelaide Kane||Mary Stuart|
|Megan Follows||Queen Catherine|
|Toby Regbo||Prince Francis|
|Celina Sinden||Greer Norwood|
|Caitlin Stasey||Lady Kenna|
|Anna Popplewell||Lady Lola|
|Alan van Sprang||King Henry|
|Michael Therriault||Lord Castleroy|
|Gil Darnell||Duke of Guise|
|Ari Cohen||Robert Norwood|
|Jenna Warren||Ainsley Norwood|
|Ella Sinatra Querin||Colleen Norwood|
|Brendan Cox||Duke Francis|