Complex sentence: Confederates surrendered their weapons and were allowed to return to their homes, and at Lee's request, Grant also allowed them to keep their horses, all on the condition that they would not take up arms against the United States.
Split into simpler sentences: Confederates surrendered their weapons and were allowed to return to their homes. At Lee's request, Grant also allowed them to keep their horses, all on the condition that they would not take up arms against the United States.