To commemmorate the battle of Aljubarrota, here’s a contribution that presents the other side of History: a “real” (that’s its name) coin with the effigy of Queen Beatriz of Castile, Léon and Portugal, coined at Santarém in 1384. There are only 3 specimens of this issue. By the way, does someone know what happened to the specimen held by the Espírito Santo bank?
In my opinion, she was the “de iure” Portuguese queen from 22nd October 1383 until 14th August 1385, since she was the legitimate heir of King Ferdinand I of Portugal according to the sucession laws of the kingdom. The treaty of Salvaterra de Magos was worth less than the paper it was written here during the sucession crisis of 1383-1385, since many of its complicated dispositions could never be followed and the party of John, headmaster of the Order of Avis, overthrew Leonor Teles’ power at Lisbon on 6th December 1383, to don’t refer the fact medieval treaties were only in vigour as long as they were useful to both parties. This meant that afterall the main argument of João das Regras (a at the “Cortes of Coimbra” of 1385 (illegal as a regent couldn’t call the “Cortes”, which were equivalent to the Estates-General in other realms at this time) was afterall heavily flawed and his other argument the John I of Castile was schismatic isn’t exactly worth anything if we remember the constant switches of side by Ferdinand I regarding the Great Schism of 1378. Also the arguments of a salic law were baseless in 14th century Portugal and a manipulation by the famous jurist, while as far as we know Count Andeiro wasn’t yet Leonor Teles’ lover in 1372-early 1373, so we can safely assume Beatriz was legitimate.
This means that afterall we could make the case John I’s invasions in 1384 and 1385 were completely legitimate in order to defend his wife’s claim to the throne and keep the social “status quo” in Portugal (we must remember this crise also involved a “social revolution” as the result of the socioeconomic pressures accumulating in the kingdom during the 14th century).
Moreover, John I of Portugal was an usurper who slowly used the popular discontent against the Portuguese elites and the queen Leonor Teles to slowly gain power over the kingdom and gained the throne through the right of conquest. In this he was aided by sectors of the lesser nobility, including Nuno Álvares Pereira, who was really in many ways a king maker in his help to John (although the latter also deserves credit for his patience and political skills, as well as for the rearguard charge at Aljubarrota that saved the day for his side), and the bourgoisie and clergy of Lisbon and Porto (the latter was coerced at Lisbon after the death of archbishop Martinho). This doesn’t mean that what we’d call “illegal” or “nasty” (in a more colloquial way) acts didn’t have “positive” effects from a Portuguese point of view, since it guaranteed Portuguese independence, yet it wasn’t clear Portugal would lose its independence in anyway since Henry III of Castile was the Castilian heir, so if Beatriz had a child we’d see a change of dynasty, but not the loss of independence (assuming her offspring didn’t die), so we could have a similar case with that of Ferdinand I of Aragon or a case closer to the one of Jogaila in Poland. The future of the Portuguese throne was completely open by 1383 with Beatriz (and probably would end the first way, in my view, if Beatriz had her claims triumphant at Aljubarrota, since she lived until at least 1412, if not until 1431, and I don’t know any claims of infertility).
Finally, I want to add that, although the discussions on the rights of the several sides of this dispute might be endless, by August of 1385 this didn’t matter: the country was in civil war with a Castilian intervention and there were 2 persons claiming to be the heirs of Ferdinand I of Portugal (3, if we count Beatriz’s husband) who had resources to stake their claims. Both sides thought themselves to be righteous and there was no turning point: the Portuguese throne and the future of the kingdom had to be decided on the battlefield. That’s the importance of Aljubarrota, on the sunny day of 14th August 1385.