Franz Freiherr von John was born in Bruck an der Leitha as the fourth child of an Austrian officer. He was schooled at the military academy in Wiener Neustadt and joined the "Archduke Franz Karl" Infantry Regiment Nr. 52 in 1835 as a lieutenant. In 1845 he served as a Lieutenant on the General Quartermaster staff. In 1848 he served under Radetzky as a captain during the First Italian War of Independence where he distinguished himself at Goito.