As a young man in Rodney, Mississippi, he worked as a merchant outfitting parties leaving for Texas.
After applying to empresario Joseph Vehlein for land in 1835, he and family first moved to Austin in the fall of 1839.
When Indian attacks on the then-frontier town became too much, Duggan moved his family, eventually settling just east of Seguin in present-day Guadalupe County, Texas.
After a failed bid for re-election, Duggan was again elected in 1858, this time from the 27th district, to serve in the Eighth Legislature.
After losing a re-election bid to Stephen Heard Darden (for the 25th district), Duggan, at age 46, joined the Texas militia.