Philadelphia campaign
The Philadelphia campaign was a British military campaign during the American Revolutionary War designed to gain control of Philadelphia, the Revolutionary-era capital where the Second Continental Congress convened, formed the Continental Army, and appointed George Washington as its commander in 1775, and later authored and unanimously adopted the Declaration of Independence the following year, on July 4, 1776, which formalized and escalated the war.
In the Philadelphia campaign, British General William Howe failed to draw the Continental Army under George Washington into a battle in North Jersey. Howe then embarked his army on transports, and landed them at the northern end of the Chesapeake Bay, where they began advancing north toward Philadelphia. Washington prepared defenses against Howe's movements at Brandywine Creek, but was flanked and beaten back in the Battle of Brandywine on September 11, 1777. After further skirmishes and maneuvers, Howe entered and occupied Philadelphia. Washington then unsuccessfully attacked one of Howe's garrisons at Germantown prior to retreating to Valley Forge for the winter, where he and 12,000 faced the harshest winter of the war, including insufficient food and clothing.
Howe's campaign was controversial because, while he succeeded in capturing the revolutionary capital of Philadelphia, he proceeded slowly and did not aid the concurrent campaign of John Burgoyne further north, which ended in disaster for the British in the Battles of Saratoga and brought France into the war. Howe resigned during the occupation of Philadelphia and was replaced by his second-in-command, General Sir Henry Clinton.
In 1778, Clinton was ordered to evacuate Philadelphia and consolidate his troops in New York City, in anticipation of a combined Franco-American attack there. Many Loyalists also left Philadelphia, fearing persecution. Washington's forces shadowed the withdrawing British Army until they clashed at the Battle of Monmouth, one of the war's largest battles.
At the end of the Philadelphia campaign in 1778, the two armies found themselves in roughly the same strategic positions that they had been in before Howe launched the attack on Philadelphia.
History
British plan to capture Philadelphia
Following William Howe's capture of New York City and George Washington's success in the Battles of Trenton and Princeton, the two armies settled into an uneasy stalemate in the winter months of early 1777. While punctuated by numerous skirmishes, the British Army continued to occupy outposts at New Brunswick and Perth Amboy in New Jersey.In 1777, Howe proposed to George Germain, the British civilian official responsible for war's conduct, that British expedition be launched with the goal of capturing Philadelphia, the seat of the rebellious Second Continental Congress. Germain approved Howe's plan, although with fewer troops than Howe requested. He also approved plans by John Burgoyne for an expedition to "force his way to Albany" from Montreal. Germain's approval of Howe's expedition included the expectation that Howe would be able to assist Burgoyne, effecting a junction at Albany between the forces of Burgoyne and troops that Howe would send north from New York City.
Howe decided in early April 1777 against taking the British Army over land to Philadelphia through New Jersey since this route would entail having to cross of the broad Delaware River under hostile conditions and likely require the transportation or construction of necessary watercraft. Howe's plan, sent to Germain on April 2, isolated Burgoyne from any possibility of significant support, since Howe instead would take the British Army to Philadelphia by sea, and the New York garrison would be too small for any significant offensive operations up the Hudson River to assist Burgoyne.
Washington realized that Howe "certainly ought in good policy to endeavor to Cooperate with Genl. Burgoyne" and was baffled why he did not do so. Washington at the time and historians ever since have wondered why Howe was not in place to come to the relief of Burgoyne, whose invasion army from Canada was surrounded and captured by the Americans in October. Historians agree that Lord Germain did a poor job in coordinating the two campaigns. Following Howe's capture of New York City and Washington's retreat across the Delaware River, Howe wrote to Germain on December 20, 1776, proposing an elaborate set of campaigns for 1777. These included operations to gain control of the Hudson River, expand operations from the base at Newport, Rhode Island, and take Philadelphia, the seat of the rebel Continental Congress. The latter Howe saw as attractive, since Washington was then just north of the city: Howe wrote that he was "persuaded the Principal Army should act offensively , where the enemy's chief strength lies." Germain acknowledged that this plan was particularly "well digested", but it called for more men than Germain was prepared to provide. After the setbacks in New Jersey, Howe in mid-January 1777 proposed operations against Philadelphia that included an overland expedition and a sea-based attack, thinking this might lead to a decisive victory over the Continental Army. This plan was developed to the extent that in April Howe's army was seen constructing pontoon bridges; Washington, lodged in his winter quarters at Morristown, New Jersey, thought they were for eventual use on the Delaware River. However, by mid-May Howe had apparently abandoned the idea of an overland expedition: "I propose to invade Pennsylvania by sea... we must probably abandon the Jersies."
Howe's decision to not assist Burgoyne may have been rooted in his perception that Burgoyne would receive credit for a successful campaign, even if it required Howe's help. This would not help Howe's reputation as much as if the Philadelphia campaign succeeded. Historian John Alden notes the jealousies among various British leaders, saying, "It is likely that was as jealous of Burgoyne as Burgoyne was of him and that he was not eager to do anything which might assist his junior up the ladder of military renown." Along the same lines Don Higginbotham concludes that in Howe's view, " was Burgoyne's whole show, and consequently he wanted little to do with it. With regard to Burgoyne's army, he would do only what was required of him." Howe himself wrote to Burgoyne on July 17: "My intention is for Pennsylvania, where I expect to meet Washington, but if he goes to the northward contrary to my expectations, and you can keep him at bay, be assured I shall soon be after him to relieve you." He sailed from New York not long after.
Washington's Continental Army had been encamped primarily at Morristown, New Jersey, although there was a forward base at Bound Brook, only a few miles from the nearest British outposts. In part as a retaliatory measure against the ongoing skirmishes, General Charles Cornwallis executed a raid against that position in April 1777, in which he very nearly captured the outpost's commander, Benjamin Lincoln. In response to this raid, Washington moved his army forward to a strongly fortified position at Middlebrook in the Watchung Mountains that commanded likely British land routes toward Philadelphia.
For reasons that are not entirely clear, Howe moved a sizable army to Somerset Court House, south of New Brunswick, New Jersey. He performed this move as a feint to draw Washington out from his strong position, but it failed since Washington refused to move his army out in force. Washington had intelligence that Howe had not brought watercraft or the necessary equipment for constructing them, so this move seemed unlikely to him to be a move toward the Delaware River. When Howe eventually withdrew his army back toward Perth Amboy, Washington did follow. Launching a lightning strike, Howe sent forces under Cornwallis in an attempt to cut Washington off from the high ground; this attempt was foiled in the Battle of Short Hills. Howe then withdrew his troops to Perth Amboy, embarked them on transports, and sailed out of New York harbor, destined for Philadelphia.
Washington did not know where Howe was going. Considering the possibility that Howe was again feinting, and would actually sail his army up the Hudson to join with Burgoyne, he remained near New York. Only when he received word that Howe's fleet had reached the mouth of the Delaware, did he need to consider the defense of Philadelphia. However, the fleet did not enter the Delaware, instead continuing south. Uncertain of Howe's goal, which could be Charleston, South Carolina, he considered moving north to assist in the defense of the Hudson, when he learned that the fleet had entered the Chesapeake Bay. In August, he began moving his troops south to prepare the city's defenses. General John Sullivan, who commanded the Continental Army's troops facing Staten Island, had, in order to capitalize on perceived weaknesses of the British position there following Howe's departure, attempted a raid on August 22, that failed with the Battle of Staten Island.
Capture of Philadelphia
In late August, British Army General Howe landed 15,000 troops at the northern end of the Chesapeake Bay, about 55 miles southwest of Philadelphia. Continental Army General Washington positioned 11,000 men between Howe and Philadelphia but was outflanked and driven back at the Battle of Brandywine on September 11, 1777. The Continental Army suffered over 1,000 casualties, and the British lost about half that number.The Continental Congress was once again forced to abandon Philadelphia, relocating first to Lancaster, Pennsylvania, and later York, Pennsylvania. British and Revolutionary forces maneuvered around each other west of Philadelphia for the next several days, clashing in minor encounters such as the abortive Battle of the Clouds and the so-called "Paoli Massacre". On September 26, Howe finally outmaneuvered Washington and marched into Philadelphia unopposed. Capture of the rebel capital did not bring the end to the rebellion as the British thought it would. In 18th-century warfare, it was normal that the side who captured the opposing force's capital city won the war, but the Revolutionary War would continue for six more years until 1783 because of the rebels' unconventional warfare tactics.
After capturing Philadelphia, the British garrisoned about 9,000 troops in Germantown, five miles north of Philadelphia. On October 2, the British captured Fort Billingsport, on the Delaware River in New Jersey, to clear a line of chevaux de frise obstacles in the river. The idea of placing those obstacles is attributed to Benjamin Franklin, and they were designed by Robert Smith. An undefended line had already been taken at Marcus Hook, and a third line was nearer Philadelphia, guarded by Fort Mifflin and Fort Mercer. Washington unsuccessfully attacked Germantown on October 4, and then retreated to watch and wait for the British to counterattack. Meanwhile, the British needed to open a supply route along the Delaware River to support their occupation of Philadelphia. After a prolonged defense of the river by Commodore John Hazelwood and the Continental and Pennsylvania Navies, the British finally secured the river by taking forts Mifflin and Mercer in mid-November, although Mercer was not taken until after a humiliating repulse. In early December, Washington successfully repelled a series of probes by General Howe in the Battle of White Marsh.
Washington's problems at this time were not just with the British. In the Conway Cabal, some politicians and officers were unhappy with Washington's performance in the campaign and began secretively discussing Washington's removal. Offended by the behind-the-scenes maneuvering, Washington laid the whole matter openly before Continental Congress. In response, his supporters rallied behind him, and Washington's leadership was reassured.