Riley was born to an Irish-Catholic couple, Bennet Riley and Susanna Ann Drury, in
St. Mary's, Maryland, 1787. His father apprenticed him to a cobbler; later, he served as a foreman in a shoe factory. After his father's death in 1811, he signed up for service on a
privateer. Riley married Arabella Israel, of Philadelphia, on 9 November 1834, at the Jefferson Barracks,
Lemay, Missouri. They had eight children: William Davenport Riley and Samuel Israel Riley, twins, died in
Fort King, Florida, on 15 and 17 November 1841; Bennet Israel Riley, born 1835 in Massachusetts, served in the Navy and died aboard the war-sloop , which disappeared with all hands in September 1854; Mary, born 1836; Arabella I. Riley, 1837–1916) (never married); George, born 1838; and Edward Bishop Dudley Riley (1839–1918), whose military career was split between the Union and Confederate armies.
Ulysses S. Grant described Bennet Riley as "the finest specimen of physical manhood I had ever looked upon...6'2 (190 cm) in his stocking feet, straight as the undrawn [sic] bowstring, broad shouldered with every limb in perfect proportion, with an eagle and a step as light as a forest tiger." An accident or injury in his youth caused him to lose part of his palate, and he spoke with a hoarse voice. ==War of 1812==