Final answer:
The Union's plan to capture Richmond, the Confederate Capital, faltered mainly due to the weak Union General McClellan and his cautious nature. McClellan's original plan to attack from the east was hindered by Confederate defenses and adverse weather conditions. This allowed Confederate General Lee to plan his attack and strengthen the defenses of Richmond.
Step-by-step explanation:
The subject of this question is History and it is at a High School level. The Union's plan to capture Richmond, the Confederate Capital, faltered mainly due to the weak Union General McClellan. McClellan's original plan was to attack the Confederates from the east by landing his army at Fort Monroe, Virginia. However, his advance was slowed by Confederate defenses and the weather.
Additionally, McClellan's cautious nature and reluctance to engage in battle hindered the Union's progress. These factors gave Confederate General Lee the opportunity to plan his attack, organize his army, and strengthen the defenses of Richmond.