Benjamin Montgomery was born into slavery in 1819 in Loudon County, Virginia.
Montgomery obtained employment at a general store owned by his master Joseph Davis. He would eventually take over the entire purchasing and shipping operations of the store. During those days, merchandise was shipped by boat on the rivers connecting counties and states. However, a timely shipment was not guaranteed since the depths of water in different spots throughout the river made navigation difficult.
In an effort to expedite the shipment of merchandise, Montgomery invented a propeller that could cut into the water at different angles, thus allowing the boat to navigate more easily through shallow water.
Montgomery attempted to patent his invention after regaining his freedom but was rejected again.