English amphibious expedition led by General at Sea William Penn, father of the founder of Pennsylvania, and General Robert Venables invaded Spanish territory in the West Indies with the objective of capturing Hispaniola. It was one of the strongest ever to sail from England, with some 3,000 marines under the command of General Robert Venables, further reinforced in Barbados, Montserrat, St. Kitts and Nevis. Although Cromwell had previously been interested in the possible acquisition of Hispaniola island, the expedition's commanders were given the freedom to determine their own priorities in the circumstances they faced on arrival. Several options were considered, including a landing on the coast of Guatemala or on Cuba. Both were discounted, as Penn and Venables decided to attempt to repeat Drake's attack on Santo Domingo on Hispaniola. However, the 1655 Siege of Santo Domingo failed because the Spanish had improved their defences in the face of Dutch attacks earlier in the century. Cromwell, on the other hand, saw the Hispaniola defeat as God's judgement. Despite various subsequent successes, the defeat made the whole operation against the Spanish West Indies a general failure. Venables and Penn were imprisoned therefore in the Tower of London on their arrival on England. Jamaica was the casus belli that resulted in the actual Anglo-Spanish War in 1655. Weakened by fever, the English force then sailed west for the Colony of Santiago (present-day Jamaica), the only Spanish West Indies island that did not have new defensive works. They landed in May 1655 at a place called Santiago de la Vega, now Spanish Town. They came, and they stayed, in the face of prolonged local resistance that was reinforced by troops sent from Spain and New Spain (México). In 1657 the English Governor invited the Buccaneers to base themselves at Port Royal on Santiago, to deter the Spanish from recapturing the island. For England, Jamaica was to be the "dagger pointed at the heart of the Spanish Empire", although in fact it was a possession of little value then. Cromwell, despite all difficulties, was determined that the presence should remain, sending reinforcements and supplies. New Spanish troops, sailing from Cuba, lost the Battle of Ocho Rios in 1657 and the Battle of Rio Nuevo in 1658, failing in their attempts to retake Jamaica. Nevertheless, the fear of another invasion meant that the English Governor of Jamaica Edward D'Oyley felt his new duty was to