The British Royal Navy though large and in need of some upgrading if it had been actually fully used could have cut up the American colonies. The British failed in that they did not use their navy enough or correctly and instead used their land forces too much. Prior to Saratoga the Revolution could have been crushed if British Naval squadrons in combine arms with the army seized and blockaded American major ports and bays. The Hudson, Great Lakes, and St Lawrence they would and could have seized Boston, Portsmouth, and Newport News, RI. Cutting off New England. Likewise with the Delaware Bay and Chesapeake patrolled they could seize Baltimore, Annapolis, Philidelphia, Newport Va and Delaware and their major ports. This would have had the effect of demoralizing and cutting off funds for Revolutionaries as did OTL with the taking of Charleston and Savannah. If Burgoyne, Howe, Cornwallis and the others had simply stayed put in the major ports and not gone gala chanting and stirring up the people in the countryside the Continental Army would be unable to dislodge the Continentals who would be penned in te backwoods with their backs to the wilderness. With each region isolated its possible that the British could have destroyed each Rebelling state government and force.
With this the Continental Congress would be bled of money and force which the only option would be to give into the British or seek a compromise. All by 1778, before Saratoga and the French, Dutch, an Spanish could enter the conflict. Even still this strategy would stop any European reinforcements from entering the conflict such as the OTL French attack in Charleston, and perhaps catch the French forces before they arrive in Newport.