Late in the XIV century / early in the XV century, 12 English knights insulted 12 English ladies*, who presented a formal complaint to the Duke of Lancaster.
* Who were told to be 'ugly' and not deserving to be around the Duchess as ladies in waiting.
Being a friend – and the father in law - of the King of Portugal D. João I (1357-1433), the Duke asked D. João I for help (D. João I was the father of D. Duarte).
'History' states that, as a reply to this call out for help, twelve Portuguese knights** were trusted with the mission of avenging the ladies' honour.
** 'The Twelve of England' are mentioned in King D. Duarte’s 15th century "A arte de bem Cavalgar" English translation
Though 11 of them departed by ship from Porto, this special group's most well known member, Alvaro Gonçalves Coutinho - nickname 'O Magriço' ('the thin one') - opted to travel by land, going through Spain, Burgundy, France and Flanders.
A detailed description of the tournament can be found in a document from 1599 (Rui de Pina – Chronica d’El-Rei D. Duarte – Published by Alfredo Coelho de Magalhães).
Additionally, in a letter dated December 26th 1411 from the Duke of Burgundy and Earl of Flanders to Portuguese King Dom João I, the Duke thanks for the services supplied by 'O Magriço'.
This event wasn't comprised of jousting, as no horses were involved. Instead, the fights began with combatants using shields and maces and, later on, switching to swords.
Fights were bloody and, according to the accounts available, went on for a couple of hours, which even included a rest break. Ultimately, the tournament was ended by the Duke of Lancaster when 8 Englishmen were deemed to be severely wounded ... meaning that the overall result was that of 8 wins for the Portuguese and 4 draws.
Of the "twelve of England", 3 stayed in England and never returned to Portugal, including Dom Alvaro de Almada, who later became the Earl of Avranches, and is most well known for the following episode.
In 1449, 11 years after D. Duarte’s death, a battle took place in Alfarrobeira - near Lisbon - between the the King's army (D. Afonso V) and his uncle's (who was also his father-in-law) D. Pedro, D. Duarte's brother.
With the kingdom at stake, the Earl of Avranches sided with D. Pedro.
The latter, upon realizing the tremendous disadvantage they were facing, asked the Earl of Avranches:
"Earl! What are we going to do?"
To which he got the following infamous reply:
We shall have dinner here and a late supper in Hell!"
And so it was, the Earl of Avranches and D.Pedro both died in battle.
"Live by the sword, die by the sword"