Complex sentence: Colonel Williamson lost a leg at the battle of Resaca, May, 1864, and J. T. Smith, was appointed Colonel, was killed in battle July 28, James P. Eagle then succeeding him as Colonel of the regiment.
Split into simpler sentences: Colonel Williamson lost a leg at the battle of Resaca, May, 1864, and J. T. Smith, was appointed Colonel. After Smith was killed in battle on July 28, James P. Eagle then succeeded him as Colonel of the regiment.