Final answer:
The British ships were heading to Concord to seize military supplies and arrest Patriot leaders, stopping at Nantasket Road because Boston was nearly an island, requiring troops to be ferried across the bay. This unexpected disembarkation led to a difficult and exposed march, as colonists were pre-warned and ready to engage in combat along the route.
Step-by-step explanation:
The British ships were heading towards Concord with the intention to confiscate weapons and ammunition and arrest leaders of the Patriot movement. They stopped at Nantasket Road off Braintree due to the difficult logistic situation. Boston was effectively an island, connected only by a narrow passage to the mainland. To avoid marching, the British troops were ferried across the bay, but they had to disembark in difficult conditions, getting wet and muddy, which made their subsequent march to Concord even more challenging. Moreover, the colonists were alerted to their presence by a sophisticated system of signals, and the British found themselves exposed to attacks from the militias along the route. Several factors contributed to the British decision to stop at Nantasket Road: logistical concerns, the geographic constraints of Boston, and the need to transport a large number of troops efficiently. Despite this unfortunate start, the British troops formed up and continued on their mission. However, they faced constant harassment from Patriot fighters who used guerrilla tactics, exploiting the terrain to their advantage.