As a prior enlisted Soldier, he rose to the rank of Sergeant First Class before receiving a commission in the Army Medical Specialist Corps.

[6] Burnham was serving as an Evacuation Specialist with HHC, 1/5 Infantry Battalion at Fort Lewis, Washington, when he decided to compete in the preliminary competitions for the 2003 Soldier of the Year.

Burnham won the competition, consisting of several grueling mental and physical tasks, and was reassigned to Washington, DC to serve as an ambassador for the Army.

[9] Based on the board results from summer 2007 and after completing prerequisite courses at San Antonio College, Burnham attended the Interservice Physician Assistant Program at Fort Sam Houston beginning in April 2009 and graduated with a bachelor's degree in biology from the University of Nebraska Omaha in May 2010 and subsequently completed his master's in Physician Assistant Studies at Tripler Army Medical Center in Honolulu, Hawaii in 2011.

[10] After receiving his commission, attending the Basic Officer Leader Course at Fort Sam Houston, and moving to Fort Drum, New York, he assumed his duties as Special Staff Officer to the Commander and Squadron Physician Assistant with the 1st Squadron, 89th Cavalry Regiment, 2nd Brigade Combat Team, 10th Mountain Division.

Shortly after being promoted to Captain, Burnham completed his first tour to Afghanistan while serving as the Special Staff Officer to the Commander and Battalion Physician Assistant with the 1st Battalion, 32nd Infantry, 3rd Brigade Combat Team, 10th Mountain Division, in support of Operation Enduring Freedom 13-14, where he was awarded the Bronze Star medal and was recognized by the US Central Command Surgeon for outstanding leadership and battlefield medicine with the inaugural Ditch Medicine Award.