The conditions of the Treaty of El Pardo (1778) have always been a mystery to me. From Wikipedia:
The Treaty of El Pardo was signed on March 11, 1778 between Queen Maria I of Portugal and King Charles III of Spain. The treaty aimed at resolving long-standing territorial disputes arising from non-observance of the terms of the Treaty of Tordesillas and subsequent treaties to resolve the matter. Most recently, was the continued strife at the southern tip of Portuguese advance into region of the Misiones Orientales and present-day Uruguay and parts of Paraguay, the Spanish–Portuguese War, 1761–1763 and the Spanish–Portuguese War, 1776–1777.
The main issue was the penetration by Portuguese Bandeirantes deep into the South American hinterland, in violation of the division imposed by the treaty of Tordesillas. The new treaty recognised the principle of uti possidetis, already followed in earlier treaties. However, doing so recognised Portuguese dominion over vast swathes of present-day Brazil, whereas the Spanish had stayed out of Africa in observance of the Treaty of Tordesillas. To compensate for this imbalance, Queen Maria agreed to cede the islands of Annobón and Bioko (Fernão Pó) to King Charles, as well as the Guinea coast between the Niger River and the Ogoue River. The island of Formosa (named Fernão do Pó during Portuguese rule) was officially renamed and recognized as Fernando Poo.
Now, this all sounds fine, except, looking at a map, it starts to make less sense:
The Spanish decided to take Annobon instead of, say, Principe. Why? I understand they may have had a limited offer (maybe the Portuguese preferred to keep Principe, it was more valuable) but is this the only reason behind it?
It even led to Annobon being in a state of virtual anarchy for some time (due to rejecting the Spanish colonization and being hard to manage from such a large distance from the Rio Muni and Fernando Po colonies).
Can anyone shed some light on this subject?