Slave Inventor Denied Patent—Then Bought His Plantation" Benjamin Montgomery's story reveals one of the most extraordinary examples of genius suppressed by systemic injustice in American history. Born enslaved in 1819, Montgomery became a self-taught engineer, architect, and inventor who designed a revolutionary steamboat propeller for shallow waters. When he tried to patent his invention in 1858, he was denied—not because it wasn't innovative, but because the law refused to recognize enslaved p