James Camp Tappan was born on 9 September 1825 in Franklin, Tennessee where his parents had migrated from Newburyport, Massachusetts. Tappan attended Exeter Academy in New Hampshire and graduated from Yale University in 1845. Tappan studied law at Vicksburg, Mississippi and was admitted to the bar in 1846.
Tappan soon moved to Helena in Phillips County, Arkansas. He was elected to two terms in the Arkansas legislature and served as a circuit court judge.
At the outbreak of the Civil War Tappan's sympathies lay with the Confederate cause despite his northern parents and he joined the Confederate army. In May 1861 he received a commission as Colonel of the 13th Arkansas Infantry.
Tappan commanded his regiment at the Battle of Belmont and made repeated charges on the Hornet's Nest at the Battle of Shiloh. After Shiloh Tappan took part in the Kentucky Campaign and fought at the Battle of Richmond and the Battle of Perryville.
On 5 November 1862 Tappan received his commission as Brigadier General and was transferred to the Trans-Mississippi Department under General Sterling Price. Tappan commanded his brigade at the Battle of Pleasant Hill in Louisiana defending against General Nathaniel Banks' Red River Campaign of 1864. After the fight at Pleasant Hill Tappan's brigade was moved northward back into Arkansas to meet General Frederick Steele at the Battle of Jenkins' Ferry. Tappan and his brigade also took part in Price's Missouri Raid.
After the war Tappan returned to Helena, Arkansas and took up his law practice where he established himself as the dean of the Arkansas bar. Tappan also engaged in politics after the reconstruction period and served again in the Arkansas legislature. Tappan was nominated by the Democratic party for Governor of Arkansas on two occasions but declined to run.
James Camp Tappan died on 19 March 1906 in Helena, Arkansas. He is buried at Maple Hill Cemetery in Helena near the graves of General Thomas C. Hindman and Patrick Cleburne.