A Fire Mark is a metal plaque that was attached to a building to signify that the building was insured and by which company. The earliest of these Fire Marks date back to the Great Fire of London in 1666. After this fire, London created an insurance system and "fire companies". Once you paid your insurance and affixed the fire mark to your structure, you would have the services of one of the city charted companies. Fire marks (insurance company marks) were used in the U.S. from about 1750 to around 1900.
In the early days of the U. S., there were no municipal fire departments. Fire brigades were sometimes either owned, or paid, by insurance companies (or assurance companies) or supported by the community. Some stories tell that in some communities the fire brigade only responded to protect the property of those who had the insurance who owned this fire brigade. In other cities the fire brigades might have been independent companies. The story you hear, tells of the money going to the fire brigade who was successful in staking a claim on the property, which was on fire. One method of claiming a structure was to place a ladder on it. The first company to do so was allowed to fight the fire and was therefore paid by the insurance
company. As you can imagine, there were problems with this system. Fire companies would have people whose main job it was to (A) ladder the building and (B) prevent the other company from doing so. There are many stories of different fire brigades being involved in fist fights, in the front yard, while the structure burned.