Final answer:
American forces managed to trap the British as they tried to retreat from Washington.
Step-by-step explanation:
The event that stopped the flames from burning down Washington completely and scared the British troops was Option E: American forces managed to trap the British as they tried to retreat from Washington. During the War of 1812, the British set fire to several buildings in Washington, including the White House and the Capitol. However, as they attempted to withdraw from the city, they were outnumbered and outmaneuvered by American forces, leading to their retreat and the end of the burning of the city.
Learn more about The events that stopped the burning of Washington during the War of 1812