The “Harlem Hellfighters” helped the US win World War I. The Black infantry unit was one of the most decorated regiments at the time, even as most of its members were met with racism and disregard upon their return home.The “Harlem Hellfighters” helped the US win World War I. The Black infantry unit was one of the most decorated regiments at the time, even as most of its members were met with racism and disregard upon their return home.