What does in hoc signo vinces to knights templar?

Answer 1

Freely translated as With this sign you will conquer(lit. In this sign you will conquer), the words that an angel told the Roman Emperor Constantine, this saying refers to the uniform of the Templars, which was a red cross (the sign*).

*In the the story of the angel speaking to Constantine, the sign was, in fact, a chi ro symbol, which, though referencing Christ (Chi is "H" in Greek and ro is "R"), is not the cross per se (in itself).

Answer 2

"In hoc signo vinces" is Latin for "In this sign you will conquer." It was a motto used by the Knights Templar, symbolizing their belief in the power of the Christian faith to achieve victory. The phrase is associated with a vision allegedly seen by Roman Emperor Constantine before the Battle of Milvian Bridge in 312 AD.