Here's a breakdown of the likely origin:
* "Dukes" as a slang for fists: The word "dukes" was used as slang for fists in the 1800s, likely stemming from the association of the Duke of Wellington with boxing.
* Boxing terminology: In boxing, "to put up your dukes" means to raise your fists in a fighting stance.
* Popularity of boxing: Boxing was a popular sport in the 19th and 20th centuries, making the phrase "put up your dukes" widespread in everyday speech.
Therefore, the phrase likely originated from the boxing world, where fighters would "put up their dukes" to prepare for a fight. This meaning then transitioned into general slang, signifying a readiness for a physical confrontation.
While the exact origin remains uncertain, the connection to boxing seems the most plausible explanation for the phrase's popularity and its use today.