Final answer:
General William Howe diverted his forces to take Philadelphia instead of going to Albany to meet General Burgoyne's troops, leading to Burgoyne's isolation and surrender after the Battles of Saratoga.
Step-by-step explanation:
Instead of moving north to Albany to meet General Burgoyne's troops as part of a planned rendezvous, General William Howe chose to embark on a separate campaign to take Philadelphia. Howe's choice to prioritize Philadelphia over supporting Burgoyne's northern campaign sapped critical troops and resources that could have contributed to a pincer movement against American forces. General Burgoyne, expecting support from Howe and General Henry Clinton, was ultimately left to fend for himself. This decision led to a series of delays and misfortunes for Burgoyne, culminating in the isolation of his forces and his eventual surrender after the Battles of Saratoga, since the coordinated three-army strategy to isolate New England failed due to Howe's diversion towards Philadelphia.