 Complete the following phrase:  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 