Havana in the late 18th century was a major port and naval base, and also the strongest fortress in Spanish America. Its royal shipyard with access to abundant supplies of resistant hardwoods was capable of building first-rate ships of the line and had been developed by the Bourbon monarchy as the most important of its three naval shipyards. There had been several previous plans to attack Havana, including one proposed to Vernon in 1739, which he rejected in favour of an attack on Porto Bello, but no successful attack since it was comprehensively fortified, and the strength of its fortifications and difficulty that large sailing warships would have in making an undetected approach from the north convinced the Spanish commanders it would be virtually impossible to capture, if its fortifications were in good order and it was properly garrisoned. Its wealth and ability to feed its population also suggested that it could resist being starved into surrender.