He was born on July 13th, 1887 at Sar Planina, Serbia. In 1905, at the age of 18, he immigrated to America.
When the US entered World War I, Mandusich immediately enrolled himself in the Army. During the battle in Amiens region in France in August of 1918, Jake, now a corporal, advanced his men at Chipilly Ridge; there were many casualties and in the heat of the battle Alex realized that all officers had been hit and that he was now the leader of his platoon. His men were pinned down by machine gunfire from a German nest thirty yards away. Under intense fire Manudsich made his way to the nest alone; he pulled out his bayonet and attacked..