France’s entry into the war with Great Britain in the spring of 1778 subsumed a war of colonial independence in an international great power struggle and expanded warfare throughout the globe. France’s open support of the United States of America blasted Britain’s last hope for reconciliation with its rebellious colonies that rested on the Carlisle peace commission, dispatched to America in April 1778. The Royal Navy now faced a formidable opponent in the French Navy, while still needing to protect British shipping from the harassment of American privateers and the warships of the ragtag Continental Navy. Were the Spanish to unite with the French, the combined Bourbon navies would overmatch the British Navy in ships of the line. While France made preparations for war, British naval strategists had to consider the very real possibility of an invasion of the British Isles.

In the spring of 1778, Continental Navy commanders confirmed the American sea forces as an active threat to British shipping in European waters. Captain John Paul Jones and the crew of Ranger took the fight to the British in April 1778 and completed one of the Continental Navy’s most celebrated cruises of the war. Ranger’s sensational raid secured Jones’s fame throughout Europe and America and struck a blow to British confidence. In a month’s cruise in the Irish Sea, Ranger captured and sank merchant shipping in the Irish Channel and captured and sent into Brest a warship of the Royal Navy, the eighteen-gun sloop-of-war Drake. Jones raided the English port of Whitehaven and attempted to kidnap a minor Scottish noble on St. Mary’s Island. These American landings on British soil led to demands on the British Admiralty from towns up and down the British coast for protection and to a fourfold increase in insurance for shipping in the Irish Sea. Ranger returned to Brest with more than two hundred British sailors, whom Jones intended to hold in France as prisoners of war until an exchange for American sailors held in British prisons could be arranged. Despite the success of the cruise, Ranger returned to France with an unhappy crew and sharp divisions among its officers.

April found Continental Navy frigate Boston, Captain Samuel Tucker, which had brought John Adams to replace Silas Deane as one of the American Commissioners in France, at Bordeaux undergoing repairs, including replacement of masts. While in port, several discontented seamen deserted and Tucker discovered and foiled a
mutinous plot.

With Continental Navy cutter Revenge, Captain Gustavus Conyngham, already an established name in the European theater, pursued his campaign against British shipping in the Atlantic. Despite British diplomatic pressure on Spain to bar American privateers from their ports, Conyngham continued operating out of Cadiz. He sent so many prizes to ports in Spain, France, and America that Revenge had to put in to Calais, France, to recruit seamen to replace men sent off as prize crews. Moving his base of operations to Corunna, Conyngham relied on the Spaniards’ turning a blind eye to his commerce raiding. The more success Conyngham had however, the louder grew British protests and the more persuasive British demands that Spanish court order him away.

In the meantime, the American Commissioners in France, Benjamin Franklin, Arthur Lee, and John Adams, wrestled with persistent problems: money, supply, and personnel requirements of the Continental Navy forces in European waters; disputes among former and current Continental Agents in the French ports and among merchants who supplied the Continental ships; and requests for aid from American sailors escaped from British prisons. The commissioners negotiated with America’s new French allies over matters as diverse as the protocol of exchanging salutes between Continental Navy ships and French forts and French naval escorts for American merchantmen.

Among the American Commissioners’ chief concerns were the hundreds of American sailors languishing in the prisons of Great Britain. Despite the rigorous punishment imposed when a prisoner was caught trying to escape, escape attempts were common and sometimes successful. In contrast to an established practice of exchanging prisoners between the Continental and British Armies, the British declined to exchange sailors. By holding captured seamen indefinitely, the British sought to cripple the ability of the Americans to man cruisers that could harry British seaborne commerce. American privateers rarely kept prisoners when they took a ship and even when they did the captured sailors were typically non-combatants in merchantmen and thus not eligible for exchange. As a result, there was little for the Americans to offer in exchange for the freedom of their own seamen. The bargaining leverage provided by Ranger’s Royal Navy prisoners, however, emboldened the commissioners to propose an exchange of captive seamen.

The French Toulon fleet, under command of Vice Admiral the Comte d’Estaing, put to sea on 13 April, it was more than a month later that it passed the Straits of Gibraltar. Adverse weather, poor sailing, and faulty equipment were factors that added to the duration of the voyage. British uncertainty over the Toulon fleet’s destination led to a period of indecision on the part of the Admiralty on how to react. There were three scenarios the British considered: D’Estaing was heading for the West Indies to capture British sugar islands; he was sailing to North America to support the Continental Army and counter British command of the sea in that quarter; or he was going to Brest in order to combine with the fleet under Comte d’Orvilliers in preparation for an invasion of the British Isles. To counter d’Estaing’s fleet, Lord Byron was put in command of a squadron that was several times alternately ordered to join Admiral Keppel’s Channel Fleet that was to oppose operations by the French fleet at Brest and to sail to reinforce Viscount Howe’s North American Fleet.

The British had reason to anticipate hostilities with Spain as well as from France. Like the French King, Spain’s Charles III was a Bourbon who harbored resentments against the British. Despite assurances to the British that they would not do so, the Spanish continued to allow American privateers in their ports, even showing preference for the Americans in plain view of British ships of war. With their own salute unanswered and requests for supplies ignored at Cadiz, the officers of H.M.S. Monarch watched as the Continental Navy cutter Revenge refit and then received a salute as it departed to prey on British shipping, while eleven other ships in the harbor flew the stars and stripes flag. One of Monarch’s officers reported twenty-two or more Spanish ships of the line at Cadiz sitting deep in the water as if preparing for a cruise. To British eyes, then, it appeared that the Spanish were on the verge of joining their French neighbors in the war.

The period from 1 April to 31 May marked the entrance of France as a belligerent into the war in support of American independence. No longer fighting alone, the Americans now had a powerful ally. While the American cause was thus advancing—even the British began to treat them with greater respect by attempting to negotiate a peace—British prospects suffered. The British faced not only greater possibility of losing their rebellious colonies, but also threats to their colonies in the West Indies and their outposts in Africa and Asia, and even invasion of the homeland. The worldwide conflict to which American rebellion had led strained the forces that the British could bring to bear, thus presenting a supreme challenge to British resources and resolve.