What was the key decision contributing to the failure of the British three-pronged plan?

The decision of General Howe to take Philadelphia played a crucial role in the British strategy during the American Revolutionary War. Initially, the British three-pronged plan aimed to capture Albany, which would effectively split the colonies and cut off New England from the south. Howe's choice to divert his forces to Philadelphia instead of supporting Burgoyne's campaign in the north meant that the British were unable to execute their coordinated attacks effectively.

This diversion weakened Burgoyne's position, as he faced the American forces largely without the expected reinforcements. Howe's focus on Philadelphia was significant because it reflected a strategic miscalculation; capturing the American capital was seen as more politically valuable than securing the northern campaign, which turned out to be detrimental. Therefore, Howe's decision not only impacted the military situation but also allowed the Americans to regroup and fortify their defenses, contributing significantly to the failure of the British plan.