Stupar is noted with the rank of
ship-of-the-line lieutenant (
Linienschiffsleutnant) in 1901-04 on the staff list of Rijeka's naval academy. His brother Anthäus was professor at the academy from 1903 until 1914. In 1907, Stupar was appointed commander of the minelayer
Salamander in
Pula. In 1910, he commanded the
torpedo boat Satellit as
corvette captain, and in 1912 was promoted to the rank of
frigate captain. In 1913 he then commanded the
light cruiser Aspern, participating in the
naval blockade of Montenegro. He assumed command of the
armored cruiser Sankt Georg in August 1913 and commanded it until October of that year. In March 1914 he became the commander of the battleship
Babenberg. He commanded the military warehouses in
Šibenik since August 1914, with the rank of battleship captain. He commanded the battleship
Erzherzog Friedrich in 1917, and on 1 May 1918 was promoted
counter admiral (i.e.
rear admiral). Stupar was twice awarded the
Military Merit Cross 3rd Class. ==References==