Not really — or at least, not in the clean “Philip II/III/IV shipped troublesome Portuguese out to Mozambique and made them mini-kings” sense.
The better answer is: the prazo-holders became little sovereigns in practice, but they were not originally designed as a Habsburg political exile program. They were more a frontier-colonial workaround: the Crown had too few troops, officials, settlers, and money to control the Zambezi valley directly, so it regularized local Portuguese/Goan/Indo-Portuguese/Afro-Portuguese occupation through Crown land grants.
A few key points:
1. The “little sovereign” part is basically fair — de facto.
Prazo holders in the Zambezi valley often held large estates, collected tribute/rents, commanded armed dependents, and governed local populations with very little effective oversight. Britannica describes prazos as “great feudal estates” begun in the 16th century and formalized in the mid-17th, whose holders gave nominal obedience to the Crown while building private armies and “virtually independent fiefdoms.” (Encyclopedia Britannica) Mozambique-history summaries likewise note that these grants were meant to legitimate Portuguese trade/settlement positions but evolved into African-Portuguese or African-Indian power centers defended by large Chikunda armies. (Encyclopedia Britannica)
2. But the motive was not chiefly “keep anti-Habsburg Portuguese nobles quiet.”
The core policy logic was imperial and fiscal: consolidate trade routes, gold/ivory access, inland garrisons, settlement, taxation, and Crown jurisdiction with minimal metropolitan investment. The Portuguese had pushed inland by the 1530s, setting up garrisons/trading posts at Sena and Tete and trying to control the gold trade; prazos helped legitimate and stabilize those positions. (Encyclopedia Britannica)
3. The chronology weakens the Philip-centered theory.
The Iberian Union lasted from 1580 to 1640. The prazo system had 16th-century roots, but it was formalized in the mid-17th century, and important later reforms/postures came after the Braganza restoration, not simply under Philip II/III/IV. (Encyclopedia Britannica) Also, be careful with numbering: Philip II of Spain was Philip I of Portugal; Philip III of Spain was Philip II of Portugal; Philip IV of Spain was Philip III of Portugal.
4. Yes, Habsburg rule over Portugal was tenuous — but that is a separate fact.
Philip initially promised to preserve Portuguese autonomy and appoint Portuguese to Portuguese administration, but later Habsburg rule violated or neglected these assurances, producing resentment over Spanish appointments, taxation, lost trade from Spanish wars, and finally the 1640 restoration revolt. (Encyclopedia Britannica) So your instinct about the political tension is good. But I would not make the prazos a deliberate safety-valve for domestic Portuguese troublemakers without stronger primary evidence.
5. There is a related “dumping ground” pattern, just not exactly your proposed mechanism.
Portuguese imperial frontiers did receive soldiers, adventurers, traders, Crown servants, Goans, mixed communities, and sometimes degredados — convicts/exiles. So Mozambique could function as a rough imperial frontier where marginal, ambitious, or unruly people were useful far away. But “politically dangerous Portuguese gentlemen were granted African estates to neutralize them under the Philips” is too neat.
So I’d phrase it like this:
The prazos were not primarily created to remove troublesome Portuguese from the kingdom during Habsburg rule. They were Crown leases/grants intended to regularize conquest, settlement, commerce, and local control in the Zambezi valley. But because Portugal lacked the means to govern the region directly, prazo-holders became quasi-sovereign frontier magnates, commanding private armies and blending Portuguese legal forms with African political realities.
Tiny sovereigns? Yes, by outcome.
Sent there as a Habsburg anti-rebellion strategy? Probably not as the main design.
