The British Army was considered the most well-trained army in the world. By the time the Revolutionary War began the army was a volunteer force due to ineffective policies of recruitment in the decade after the Seven Years War. To offset that, the British government hired German mercenaries.
The British Army used different strategies but finally failed to suppress the rebellion. They used New York as operations base because of its splendid seaport, central location, and the support of loyalist in there.
They took control of New York after the Battle of Long Island in which the Americans forces were defeated.
The American Revolution was principally caused by colonial opposition to British attempts to impose greater control over the colonies and to make them repay the crown for its defense of them during the French and Indian War (1754–63)