Final answer:
General Robert E. Lee chose to communicate directly with General Ulysses S. Grant due to military protocol and the need for direct negotiation from a position of authority. Lee's dire situation, with vastly outnumbered forces, made it imperative to deal directly with Grant, who had initiated the offer for surrender and could enforce the terms.
Step-by-step explanation:
The decision by Confederate General Robert E. Lee to speak only with Union General Ulysses S. Grant regarding the surrender of his army can be understood against the backdrop of nineteenth-century military protocol and the situation at hand. Lee recognized that Grant was not only the commander of the opposing forces but also someone who had the authority to negotiate terms. It would be appropriate, given the circumstances and the fact that Grant had initiated the correspondence, that Lee would respond in kind to his equal in command structure instead of Grant's subordinates. This adherence to military protocol was compounded by the gravity of the situation facing Lee's troops, marked by starvation, disease, and plummeting morale.
Moreover, the severity of the Confederate situation, with Lee commanding less than 35,000 men contrasted with Grant's forces of over 150,000, underscored the need for direct communication between the two leaders. Lee was aware that only Grant could provide the necessary terms that could prevent further unnecessary bloodshed and suffering. The direct exchange between Lee and Grant ensured that the negotiations were handled with the respect and formality deserved by what would be one of the final acts of the Civil War.