He was born to plantation owners Andrew Deveaux Senior and Catherine Barnwell on 30 April 1758 at St Helena's Parish in Beaufort, South Carolina.

Andrew Deveaux Junior was owner of many thousands of acres around Prince William Parish, South Carolina and Port Royal Island.

Deveaux joined the services of the British under Major General Augustine Prévost in 1779 and was present at the Siege of Savannah where the Franco-American assault was repulsed with heavy loss.

[1] Deveaux was promoted to colonel and was given command of a group Loyalist irregulars which captured two American generals in woodland ambushes.

Deveaux forced the Spanish under Don Antonio Claraco Sauz to surrender on April 17, 1783, without a single shot fired.