The British occupied New York City just after the American army abandoned it on September 15, 1776, but they lost a good deal of it just a few days later.
Late at night on the 20th, the alarm spread that New York was on fire. It was soon burning in multiple places, and the wind was spreading it fast. Many British and Hessian soldiers and sailors were sent to fight the fire, but although they worked frantically, it was not until late the next morning that they were able to stop the fire, and a large part of the city was destroyed. Some of them reported that, while fighting the fire, they had seen — and, in the fury of the moment, killed — people who were sabotaging the firefighting efforts or even setting fire to houses intentionally. One citizen of New York — a Loyalist who had just returned to his home in the city — wrote in a letter:
The destruction of the city was resolved on by some villains who were concealed in the city. Accordingly on Thursday [actually Friday] night…, when every thing was very dry, and a brisk southerly wind blew, some of them set fire to the houses near Whitehall. The fire instantly spread and raged with inconceivable violence. There were few citizens in town; the fire-engines and pumps were out of order. Two regiments of soldiers were immediately ordered into town, and many boats full of men were sent from the fleet. To these, under Providence, it is owing that the whole city was not reduced to ashes. The destruction was very great. Between a third and fourth of the city is burnt. All that is west of the new Exchange, along Broad street to the North River, as high as the City-Hall, and from thence along the Broadway and North River to King’s College, is in ruins. St. Paul’s Church and the College were saved with the utmost difficulty. Trinity Church, the Lutheran Church, the parsonage, and charity-school are destroyed. Between a thousand and fifteen hundred houses are burnt, and we are under the most dismal apprehensions that there are some more of these villains concealed in town to burn what is yet left. Our distresses were great before, but this calamity has increased them ten-fold. Thousands are hereby reduced to beggary. This scheme was executed to prevent the King’s troops from having any benefit by the city.
Was the fire started purposely by American rebels in order to destroy what the British had captured? Or was it simply the sort of accident that is bound to happen when many of the citizens move out of, and an invading army moves into, a city built mainly of wood? (The latter was the explanation that Leo Tolstoy gave for the burning of Moscow when Napoleon captured it in 1812…but that’s another story.) I don’t know for sure, but at any rate, it didn’t do the American army any harm; the British and Hessians — and, even more, the people of New York — were the ones who suffered from it.