Dunca was born in 1837 in Iași, Moldavia. He served in the Honved Army during the Hungarian Revolution of 1848 and later was a lieutenant under Figyelmessy on Sicily. Dunca came to the United States and enlisted in the Union Army in March 1862 and, due to his past military experience, was appointed captain in the 12th New York Infantry Regiment. He was later assigned as aide-de-camp to Major General John C. Fremont, whose army was operating in the Shenandoah Valley. Dunca was shot and killed by a Georgian (Pvt. John Long of Co. B, 21st Georgia Infantry) on picket duty at the Battle of Cross Keys on June 8, 1862. When the picket searched Dunca's personal effects, it was discovered that he was carrying a dispatch outlining Gen. Fremont's order of march for the day. He was buried at Perkey’s Farm, Cross Keys, Virginia, and his remains were later transferred to the Staunton National Cemetery (Section B, Grave 292).