After seeing action at Savage's Station and Malvern Hill, Maffet and the 3rd were held in reserve at Antietam during Lee's first invasion of the North. Later in 1862, Captain Maffett was a patient in Chimborazo Hospital in Richmond while recovering from typhoid fever. In December 1862, at the Battle of Fredericksburg, Maffet, by now a major, and the 3rd were positioned on Mayre's Heights above the famous stonewall manned by Cobb's Legion. Seven of the 3rd's officers were wounded at Fredericksburg, including Maffett. Shortly thereafter, his wounds not being serious, he returned home to marry Sarah Halfacre.