The Spanish plan to conquer China

The Spaniards started early: already in 1526 the conqueror of the Aztec Empire Hernán Cortés (pic)  wrote a petition the Spanish government to allow him to explore the South Seas, that is, the Pacific Ocean. Cortes plan was to start conquering some island like Malacca and then jump to the continent, just as he did starting from Cuba in his way to Mexico. 

The plan was accepted but only in 1564, Miguel López de Legazpi was given five ships and 500 soldiers to take some seven thousand islands, which he named the Philippines. Established in Manila, the Spaniards sent missionaries all over Asia. One of them, Father Martín de Rada, wrote a memorandum comparing the poverty of the islands and the wealth of China, describing its inhabitants and its (nonexistent) military capability. His idea was to abandon those miserable islands and focus on rich China. 

Next, the Spanish governor of the Philippines Francisco de Sande proposed a detailed plan. He asked for five thousand soldiers from Mexico or Peru, and smiths, carpenters, master sailors and other tradesmen to build ships in the Philippines. He even offered to pay for the expedition, which he calculated would be profitable. He described the Chinese as "bad people, drunks, cowards, submissive. Their mandarins treat the people very tyrannically". The King did not approve the plan because Spain was broke and the difficulties of communication (it took four years to send a letter and receive the answer).

Successive plans took detailed and concrete form. The number and specialties (arcabucero, piquetero, etc.) of soldiers from the Spanish dependencies was estimated, and their equipment, salaries, etc. Spain would supply bronze for the cannons and technical personnel for shipbuilding and weapons manufacture. Most of the materials were to be procured in China itself (a cannonball cost two reals in China against nine in Spain). There was a need for silver to bribe the mandarins, corrupt then as now. The expedition would include 5000 Japanese Christian soldiers who hated the Chinese, and auxiliaries from the islands. They would land in Fujian while the Portuguese forces, led by Matias de Panela, would advance from Macao. They would meet in Peking. The Ming administration was to be conserved. 

The Spanish had no doubt about the feasibility of the enterprise. Ming had two million soldiers but no discipline, no training, no loyalty, and they could be mobilized only very slowly. After 800 years of war, the Spaniard had just finished the Reconquista of the peninsula, vanquished the Turks in Lepanto, conquered the kingdoms of America, they felt unbeatable.

The Spanish analysis of the weakness of China was proved true in the next century, when Manchu nomads broke through the Great Wall and China could only present a 50,000 strong army to beat them back. The victory of Nelson at Trafalgar put an end to Spanish plans and the incoming power - England - wanted only to exploit but no to rule China.

Addenda:  Can China be conquered today? I don't think so. It has a national Han government, it has a loyal well equipped army, many bases. There was a window of opportunity under Nixon, when Brezhnev (pic) proposed a concerted nuclear attack on China. Nixon took the English road and opened China for trade. The future is unknowable.