Just realized I only answered half the question. Winfield Scott (promoted to Brigadier General 19 Mar 1814) was replaced by George B. McClellan (born 3 Dec 1826).
You're Brevet Lt. General Winfield Scott (June 13, 1786 – May 29, 1866), known as "Old Fuss and Feathers". and replaced by Maj. General George B. McClellan (December 3, 1826 – October 29, 1885). Scott was made a general on March 9, 1814. https://www.encyclopediavirginia.org/Scott_Winfield_1786-1866#start_entry
Winfield Scott was promoted to Brigadier General on March 19, 1814; breveted Maj General July 25, 1814; commander of field forces in the Second Seminole and Creek War 1836; assumed command of Eastern Division in 1837; Cherokee removal in 1838; commanding General of the US Army July 5, 1841; and resigned effective Nov 1, 1861. http://www.history.com/topics/winfield-scott
Winfield Scott's successor was George B. McClellan (b. Dec 3, 1826)
Answer - I am Winfield Scott and my replacement was George B. McClellan.
"Scott resigned in November of 1861. When he retired from the Army in November 1861, Scott had been a general longer than his successor, George McClellan, had been alive." Civil War Trust - Biography - Winfield Scott