Final answer:
Ulysses S. Grant would have supported Geary in his campaign.
Step-by-step explanation:
The leader who would have supported Geary in his campaign is d) Ulysses S. Grant.
Ulysses S. Grant was a Union general during the American Civil War and served as the 18th President of the United States from 1869 to 1877. He was known for his support of Reconstruction and his efforts to protect the rights of freed slaves. Grant would have likely supported Geary in his campaign, as Geary was also a Union general and shared similar views on Reconstruction.