First Lord of the Admiralty (third spell)
Sandwich served again as First Lord of the Admiralty in Lord North's administration from 1771 to 1782. He replaced the distinguished Admiral Sir Edward Hawke in the post. His appointment to the post followed the Falklands Crisis which had nearly seen Britain go to war with Spain over the Falkland Islands in the South Atlantic Ocean after the Capture of Port Egmont by Spanish forces. War had only been averted when Louis XVI refused to back the Spanish over the dispute. Both France and Spain resented what they considered British hegemony following the Seven Years' War, and desired to overturn the imbalance of power; war was widely expected to break out between the nations in the near future.
In 1774, only three years into his third term, Sandwich commissioned a series of ship models and a model of Chatham Dockyard as a gift to George III in an attempt to interest his king in naval matters. However, Sandwich's overall administration of the navy in the lead up to and during the American War of Independence was traditionally portrayed as being incompetent, with insufficient ships being ready for the outbreak of war with France in 1778. In 1775, Sandwich spoke vociferously in opposition to a plan for British America put forth by Benjamin Franklin and the Earl of Chatham. When Britain and France went to war, Sandwich advocated a strategy of concentrating the British fleet in European waters to deter invasion in opposition to his colleague, Lord Germain, who pushed for more ships to be sent to North America. The cabinet largely followed Sandwich's policy, retaining footholds on the American coast which could be used as naval bases, while retaining the bulk of the fleet at home. Sandwich's problems increased when Spain entered the war on France's side in 1779 giving the Bourbon fleets a numerical advantage over the Royal Navy.
Prior to 1778 Keppel failed to persuade Sandwich to ignore technical difficulties and "copper sheath only a few ships"; he was later possibly unfairly to make political capital out of this in The London Magazine, March 1781. He had remarked that coppering "gave additional strength to the navy" and he reproached Lord Sandwich with having "refused to sheath only a few ships with copper" at his request, when he had since ordered the whole navy to be sheathed. The lack of coppering the navy was one of the key reasons leading to Britain losing the Thirteen Colonies.
In 1778 the new Navy Board Controller Charles Middleton, who had the major problem at the time with supplying over 100 ships for the American Revolutionary War (1775–1783), compounded that year by French opportunism in declaring war on Britain to support the American rebels, effectively turned what was a local civil war into a global conflict. Others followed: Spain in 1779 and the Netherlands in 1780. Middleton took the view that Britain was "outnumbered at every station", and the navy was required to "extricate us from present danger". He understood that coppering allowed the navy to stay at sea for much longer without the need for cleaning and repairs to the underwater hull, making it a very attractive, if expensive, proposition. On 21 January 1779 he wrote to the Admiralty, and petitioned King George directly. The King backed him for what was an expensive process for an untested technology, and in May 1779 he placed orders at the Portsmouth Docks for coppering a total 51 ships within a year.
During 1779 a combined Franco-Spanish fleet was able to sail into the English Channel to threaten the coast of Cornwall in the initial stage of a Franco-Spanish invasion of Britain. Sandwich was criticised for the failure of the smaller British Channel Fleet to prevent this, although the invasion never materialised.
After 1778, the primary objective in the war was maintaining control over the sugar-rich West Indian archipelago. The lucrative sugar trade in the Caribbean was reckoned at the time as being of more importance to British interests than the 13 colonies. The sugar trade was paying for the costs of the American Revolutionary War (1775–1783) and the Anglo-French War (1778–1783). The Royal Navy's newly coppered ships as yet untested were used successfully by Rodney in defeating the French at the Battle of the Saintes off Dominica in February 1782.
By the time Sandwich's administration ended, he would take full credit for coppering the fleet as one of his great achievements when defending his record in office in January 1782.