In 1741, the main British campaign against Spain was a combined amphibious attack on the South American city of Cartagena, which had experienced considerable delays. Command was awarded to Admiral Edward Vernon, the victor of Porto Bello, who was given a force of 31,000 soldiers and sailors to take the city. The siege proved to be a total disaster for the British, who lost thousands of men before being forced to withdraw. Although Newcastle had issued the orders and overseen the organisation of the expedition, much of the blame for the disaster fell on the shoulders of the ailing prime minister, Walpole.