First Fruits of the French Alliance 

While the Continental Army was undergoing its ordeal and transformation at Valley Forge, Howe dallied in Philadelphia, forfeiting whatever remaining chance he had to win a decisive victory before the effects of the French alliance were felt. He had had his fill of the American war and the king accepted his resignation from command, appointing General Clinton as his successor. As Washington prepared to sally forth from Valley Forge, the British Army and the Philadelphia Tories said goodbye to their old commander in one of the most lavish celebrations ever held in America, the Mischianza, a veritable Belshazzar's feast. The handwriting on the wall appeared in the form of orders, already in Clinton's hands, to evacuate the American capital. With the French in the war, England had to look to the safety of the long ocean supply line to America and to the protection of its possessions in other parts of the world. Clinton's orders were to detach 5,000 men to the West Indies and 3,000 to Florida, and to return the rest of his army to New York by sea. 

As Clinton prepared to depart Philadelphia, Washington had high hopes that the war might be won in 1778 by a co-operative effort between his army and the French Fleet. The Comte d'Estaing with a French naval squadron of eleven ships of the line and transports carrying 4,000 troops left France in May to sail for the American coast. D'Estaing's fleet was considerably more powerful than any Admiral Howe could immediately concentrate in American waters. For a brief period in 1778 the strategic initiative passed from British hands, and Washington hoped to make full use of it. 

Clinton had already decided, before he learned of the threat from d'Estaing, to move his army overland to New York prior to making any detachments, largely because he could find no place for 3,000 horses on the transports. On June 18, 1778, he set out with about 10,000 men. Washington, who by that time had gathered about 12,000, immediately occupied Philadelphia and then took up the pursuit of Clinton, undecided as to whether he should risk an attack on the British column while it was on the march. His Council of War was divided, though none of his generals advised a "general action." The boldest, Brig. Gen. Anthony Wayne, and the young major general, the Marquis de Lafayette, urged a "partial attack" to strike at a portion of the British Army while it was strung out on the road; the most cautious, General Lee, who had been exchanged and had rejoined the army at Valley Forge, advised only guerrilla action to harass the British columns. On June 26 Washington decided to take a bold approach, though he issued no orders indicating an intention to bring on a "general action." He sent forward an advance guard composed of almost half his army to strike at the British rear when Clinton moved out of Monmouth Court House on the morning of June 27. Lee, the cautious, claimed the command from Lafayette, the bold, when he learned the detachment would be so large. 

In the early morning, Lee advanced over rough ground that had not been reconnoitered and made contact with the British rear, but Clinton reacted quickly and maneuvered to envelop the American right flank. Lee, feeling that his force was in an untenable position, began a retreat that became quite confused. Washington rode up amidst the confusion and, exceedingly irate to find the advance guard in retreat, exchanged harsh words with Lee. He then assumed direction of what had to be a defense against a British counterattack. The battle that followed, involving the bulk of both armies, lasted until nightfall on a hot, sultry day with both sides holding their own. For the first time the Americans fought well with the bayonet as well as with the musket and rifle, and their battlefield behavior generally reflected the Valley Forge training. Nevertheless, Washington failed to strike a telling blow at the British Army, for Clinton slipped away in the night and in a few days completed the retreat to New York. Lee demanded and got a court-martial at which he was judged, perhaps unjustly, guilty of disobedience of orders, poor conduct of the retreat, and disrespect for the Commander in Chief. As a consequence he retired from the Army, though the controversy over his actions at Monmouth was to go on for years. 

Washington, meanwhile, sought his victory in co-operation with the French Fleet. D'Estaing arrived off the coast on July 8 and the two commanders at first agreed on a combined land and sea attack on New York, but d'Estaing feared he would be unable to get his deep-draft ships across the bar that extended from Staten Island to Sandy Hook, in order to get at Howe's inferior fleet. They then decided to transfer the attack to the other and weaker British stronghold at Newport, Rhode Islanda city standing on an island with difficult approaches. A plan was agreed on whereby the French Fleet would force the passage on the west side of the island and an American force under General Sullivan would cross over and mount an assault from the east. The whole scheme soon went awry. The French Fleet arrived off Newport on July 29 and successfully forced the passage; Sullivan began crossing on the east on August 8 and d'Estaing began to disembark his troops. Unfortunately at this juncture Admiral Howe appeared with a reinforced British Fleet, forcing d'Estaing to re-embark his troops and put Out to sea to meet Howe. As the two fleets maneuvered for advantage, a great gale scattered both on August 12. The British returned to New York to refit, and the French Fleet to Boston, whence d'Estaing decided he must move on to tasks he considered more pressing in the West Indies. Sullivan was left to extricate his forces from an untenable position as best he could, and the first experiment in Franco-American co-operation came to a disappointing end with recriminations on both sides. 

The fiasco at Newport ended any hopes for an early victory over the British as a result of the French alliance. By the next year, as the French were forced to devote their major attention to the West Indies, the British regained the initiative on the mainland, and the war entered a new phase.