Complex sentence: He also defended his own account of the number of troops at his disposal at the battle, asking why Jackson had not challenged his numbers before now, since he had consistently reported the number of troops as being near 1,000 from the beginning of the affair.
Split into simpler sentences: He also defended his own account of the number of troops at his disposal at the battle. He asked why Jackson had not challenged Adair's numbers before now, since he had consistently reported the number of troops as being near 1,000 from the beginning of the affair.