Newton is mentioned as the first commander of the Pulaski Light Artillery in an article published in the Arkansas State Gazette, on Saturday, December 22, 1860, announcing that, "The young men of this city favorably disposed toward a Military organization which may do the ‘State some service,’ have formed under the title of the ‘Pulaski Artillery,’ and have elected Rob’t C. Newton, Captain; Wm. E. Woodruff, Jr., 1st Lieut.; L. B. Brown, 2d Lieut. and Wm. H. Causin, 3d Lieut." He resigned in early 1861 and went into the cavalry service. He joined the Confederate army as a private in 1861 and was promoted lieutenant and assistant adjutant-general on the staff of Thomas C. Hindman. He took part in the battles of Woodsonville, Shiloh, Siege of Corinth, Prairie Grove, Helana, Little Rock, and Jenkin's Ferry. He was regularly promoted, becoming colonel of the 5th Arkansas Cavalry Regiment, and was acting brigadier general in command of the Arkansas state troops at the close of the war. He was a commissioner from Arkansas to authorities at Washington in 1866 to secure representation for the state in congress.