Steve, thanks a lot for all your ideas. I do actually intend to have California break away as well some time in the 1830s (which will be an Age of Revolutions similar to 1848 in OTL).
I think the only thing to do here is for me to write a basic outline of what's going to happen, and then wait for some people who know a lot about Latin America in this period to correct me on it
Sequence of events so far is:
1. Seven Years' War similar to OTL. Not necessarily identical; POD is earlier.
2. American colonies placated with various new Whig constitutional measures.
3. Unrest in Peru. Attempt to restore an Indian state under an Inca pretender. (More widespread and successful than OTL). Spanish forces move to quell the rebellion. An army from Spain proper is deployed to LaPlata, as parts of Chile are also rising (as they were also part of the Inca state and had a large Indian population - is this plausible, anyone??)
4. The more usually loyal people of LaPlata become restless because firstly the Spanish troops are accused of acts like 'appropriating' homes and goods for military use etc., and secondly, what with all this chaos, the Spanish have shelved their plans to elevate LaPlata to Viceroyalty status.
5. After some Peterloo-like atrocity by the Spanish army, LaPlata also rises in rebellion, ironically just as the Spaniards have just about managed to crush the original revolt in Peru.
6. The war spreads. Britain, champion of Liberalism (and British interests
) declares war on Spain and supports the colonists. Analogous role to France in the OTL ARW.
7. The LaPlatans guarantee the area of OTL Argentina, Chile and Paraguay. Portugal quietly sends troops into the disputed area that would become Uruguay in OTL. The LaPlatans eventually also drive the Spaniards from Peru again, but do not support the now-crushed Inca revolt. The new LaPlatan state is not too friendly to Indians (cf. that unpopular law Max mentioned in the second post of this thread).
8. France declares war on Britain to support Spain, loses a major sea battle, but also achieves some victories. However, more importantly, the French treasury is strained by this venture, though not to the same extent as it was in OTL by supporting the ARW.
9. Treaty of London (or wherever) ; Spain relinquishes control of the former Viceroyalty of Peru and what would have become the Viceroyalty of LaPlata. The whole area eventually becomes known as the United Provinces (I believe this was a term used by the much later LaPlata/Argentina independence movement in OTL?) I also want to use the term Bolivaria as it is something we'd all recognise, but I suppose it would have to be a different Bolivar...
10. Reform movement takes hold in Spain, decides causes of Peruvian and LaPlatan rebellions were too much centralised absolutism, points to French defeat in 7 Years' War. Over the next few decades, more power will be devolved to both the two remaining Viceroyalties, New Spain and New Granada, and also to the former kingdoms making up Spain i.e. the less radical Catalonian independence movements should be sated by an autonomous Aragon. Eventually Spain will be seen as a champion of the Indians, in contrast to LaPlata, and New Spain's name is changed to Mexico to underline this. New Granada follows suit, deciding on the name Colombia.
11. French Republican Wars, analogous to OTL French Revolutionary War.
Comments?